From: Hans-Jörg Höxer Subject: Re: [EXT] Re: Reworking VMM's nested paging & guest memory (de-vmspace-ification) To: Date: Tue, 13 May 2025 15:44:23 +0200 On Tue, May 13, 2025 at 03:42:08PM +0200, Hans-Jörg Höxer wrote: > Hi, > > On Tue, May 06, 2025 at 02:34:37PM -0400, Dave Voutila wrote: > > ... > > Worked with mpi@ on tuning the lifecycle of uao's and now happy with how > > this looks. Asking for ok's at this point! > > I've tested your diff with my SEV work in progress tree and I do not > see regressions. > > The code looks code to me. actually the code looks good to me. > > > The more I looked at refining the direct use of uvm_map() the > > > more I realized this is also a good time to ditch having the vmd process > > > "prefind" ranges via mmap(2)/munmap(2) like vmd has been doing. This > > > version no longer uses UVM_FLAG_FIXED and instead let's uvm_map() > > > determine the mapping locations. The mappings are now also set with > > > UVM_FLAG_CONCEAL and MAP_INHERIT_NONE. Lastly, I now set the mappings as > > > immutable so userland can't muck with them as vmm is supposed to be > > > managing them. > > > > > > Plus, with some slight cheating by tidying up comments, the diff is > > > technically net-negative! The bulk comes from removing the hacky > > > behavior in vmd. > > > > > > diffstat refs/heads/master refs/heads/vmm-uobj-v5 > > > M sys/arch/amd64/amd64/vmm_machdep.c | 110+ 63- > > > M sys/dev/vmm/vmm.c | 104+ 46- > > > M sys/dev/vmm/vmm.h | 10+ 4- > > > M usr.sbin/vmd/vm.c | 16+ 128- > > > > > > 4 files changed, 240 insertions(+), 241 deletions(-) > > > > > > > No longer net-negative...but only net 10 lines, so not bad? > > > > 4 files changed, 255 insertions(+), 245 deletions(-) > > > > >> Today, vmm uses a UVM vmspace to represent both the nested page table > > >> (pmap) for the guest as well as guest memory in the form of amap's > > >> within the vmspace's map. This has sort of worked, but I've been hunting > > >> constant issues related to vmm triggering uvm_map_teardown inside vmm. > > >> > > >> In short, using a full blown UVM vmspace to represent a guest makes us > > >> do some funky things that are not typical in other hypervisors and leads > > >> to some lifecycle headaches: > > >> > > >> 1. vmm faults pages into the vmspace's map, which is shared via a > > >> uvm_share() function to share map entries into a target process's > > >> own address space. (This uvm_share() function exists *only* for vmm > > >> to assist in sharing guest memory between vmm's vmspace in the > > >> kernel and the vmd process's address space.) > > >> > > >> 2. This also forces use of uvm_share() for vmd child processes that > > >> need r/w access to guest memory, such as the virtio block/network > > >> emulation. > > >> > > >> 3. Teardown/cleanup means vmm's vmspace may or may not outlive the vmd > > >> process with which it's sharing mappings. > > >> > > >> Now that vmd is multi-process for guest emulation, the extra abstraction > > >> is simply a burden and increases the surface area to hunt for the source > > >> of bugs. Plus, vmm is relying on a UVM function no other kernel system > > >> uses making it a bit of a snowflake. > > >> > > >> This diff removes the use of a vmspace by: > > >> > > >> 1. creating and managing a pmap directly for representing the nested > > >> page tables (i.e. EPT page tables on Intel) and using pmap_extract / > > >> pmap_enter / pmap_remove for working with them. > > >> > > >> 2. creates and manages UVM aobjs to represent each slot/range of guest > > >> memory with an explicit size provided at creation time. These are > > >> uvm_map()'d into userland vmd processes and no use of uvm_share() is > > >> needed. > > >> > > >> 3. cleanup is simplified to dropping a refcount on the aobjs, wiping > > >> page table entries in the pmap, and then a pmap_destroy. > > >> > > >> The major changes are in vm_create, vm_teardown, svm_fault_page, and > > >> vmx_fault_page functions. There's some tidying that can be done > > >> afterwards. > > >> > > >> I've been stress testing this on one of the most cursed Intel machines > > >> that is good at finding race conditions. I've also tested it lightly on > > >> an AMD machine I own to validate SVM, so more tests are very welcome at > > >> this point. > > >> > > >> OKs welcome, but I'd prefer some test reports before looking to commit, > > >> but since we're recently unlocked from release prep, I'd prefer sooner > > >> rather than later. > > >> > > > > diffstat refs/heads/master refs/heads/vmm-uobj-v7 > > M sys/arch/amd64/amd64/vmm_machdep.c | 110+ 63- > > M sys/dev/vmm/vmm.c | 119+ 50- > > M sys/dev/vmm/vmm.h | 10+ 4- > > M usr.sbin/vmd/vm.c | 16+ 128- > > > > 4 files changed, 255 insertions(+), 245 deletions(-) > > > > diff refs/heads/master refs/heads/vmm-uobj-v7 > > commit - 51b51be201a312011f0589e0b53ca83d03adb6f3 > > commit + f855c7801b5f793a2473f6a74980edb29f1cc9d0 > > blob - 0a3be15cd64d4399bd4d038152d44763c9bebe1e > > blob + 33e312395cd9300bbaab5bd9dd44051ac72bf24b > > --- sys/arch/amd64/amd64/vmm_machdep.c > > +++ sys/arch/amd64/amd64/vmm_machdep.c > > @@ -116,6 +116,7 @@ int vmm_inject_db(struct vcpu *); > > void vmx_handle_intr(struct vcpu *); > > void vmx_handle_misc_enable_msr(struct vcpu *); > > int vmm_get_guest_memtype(struct vm *, paddr_t); > > +vaddr_t vmm_translate_gpa(struct vm *, paddr_t); > > int vmx_get_guest_faulttype(void); > > int svm_get_guest_faulttype(struct vmcb *); > > int vmx_get_exit_qualification(uint64_t *); > > @@ -900,54 +901,19 @@ vmx_remote_vmclear(struct cpu_info *ci, struct vcpu *v > > int > > vm_impl_init(struct vm *vm, struct proc *p) > > { > > - int i, mode, ret; > > - vaddr_t mingpa, maxgpa; > > - struct vm_mem_range *vmr; > > - > > /* If not EPT or RVI, nothing to do here */ > > switch (vmm_softc->mode) { > > case VMM_MODE_EPT: > > - mode = PMAP_TYPE_EPT; > > + pmap_convert(vm->vm_pmap, PMAP_TYPE_EPT); > > break; > > case VMM_MODE_RVI: > > - mode = PMAP_TYPE_RVI; > > + pmap_convert(vm->vm_pmap, PMAP_TYPE_RVI); > > break; > > default: > > printf("%s: invalid vmm mode %d\n", __func__, vmm_softc->mode); > > return (EINVAL); > > } > > > > - vmr = &vm->vm_memranges[0]; > > - mingpa = vmr->vmr_gpa; > > - vmr = &vm->vm_memranges[vm->vm_nmemranges - 1]; > > - maxgpa = vmr->vmr_gpa + vmr->vmr_size; > > - > > - /* > > - * uvmspace_alloc (currently) always returns a valid vmspace > > - */ > > - vm->vm_vmspace = uvmspace_alloc(mingpa, maxgpa, TRUE, FALSE); > > - vm->vm_map = &vm->vm_vmspace->vm_map; > > - > > - /* Map the new map with an anon */ > > - DPRINTF("%s: created vm_map @ %p\n", __func__, vm->vm_map); > > - for (i = 0; i < vm->vm_nmemranges; i++) { > > - vmr = &vm->vm_memranges[i]; > > - ret = uvm_share(vm->vm_map, vmr->vmr_gpa, > > - PROT_READ | PROT_WRITE | PROT_EXEC, > > - &p->p_vmspace->vm_map, vmr->vmr_va, vmr->vmr_size); > > - if (ret) { > > - printf("%s: uvm_share failed (%d)\n", __func__, ret); > > - /* uvmspace_free calls pmap_destroy for us */ > > - KERNEL_LOCK(); > > - uvmspace_free(vm->vm_vmspace); > > - vm->vm_vmspace = NULL; > > - KERNEL_UNLOCK(); > > - return (ENOMEM); > > - } > > - } > > - > > - pmap_convert(vm->vm_map->pmap, mode); > > - > > return (0); > > } > > > > @@ -1661,7 +1627,7 @@ vcpu_reset_regs_svm(struct vcpu *vcpu, struct vcpu_reg > > > > /* NPT */ > > vmcb->v_np_enable = SVM_ENABLE_NP; > > - vmcb->v_n_cr3 = vcpu->vc_parent->vm_map->pmap->pm_pdirpa; > > + vmcb->v_n_cr3 = vcpu->vc_parent->vm_pmap->pm_pdirpa; > > > > /* SEV */ > > if (vcpu->vc_sev) > > @@ -1675,7 +1641,7 @@ vcpu_reset_regs_svm(struct vcpu *vcpu, struct vcpu_reg > > /* xcr0 power on default sets bit 0 (x87 state) */ > > vcpu->vc_gueststate.vg_xcr0 = XFEATURE_X87 & xsave_mask; > > > > - vcpu->vc_parent->vm_map->pmap->eptp = 0; > > + vcpu->vc_parent->vm_pmap->eptp = 0; > > > > return ret; > > } > > @@ -2596,7 +2562,7 @@ vcpu_init_vmx(struct vcpu *vcpu) > > } > > > > /* Configure EPT Pointer */ > > - eptp = vcpu->vc_parent->vm_map->pmap->pm_pdirpa; > > + eptp = vcpu->vc_parent->vm_pmap->pm_pdirpa; > > msr = rdmsr(IA32_VMX_EPT_VPID_CAP); > > if (msr & IA32_EPT_VPID_CAP_PAGE_WALK_4) { > > /* Page walk length 4 supported */ > > @@ -2620,7 +2586,7 @@ vcpu_init_vmx(struct vcpu *vcpu) > > goto exit; > > } > > > > - vcpu->vc_parent->vm_map->pmap->eptp = eptp; > > + vcpu->vc_parent->vm_pmap->eptp = eptp; > > > > /* Host CR0 */ > > cr0 = rcr0() & ~CR0_TS; > > @@ -3513,7 +3479,7 @@ vmm_translate_gva(struct vcpu *vcpu, uint64_t va, uint > > > > DPRINTF("%s: read pte level %d @ GPA 0x%llx\n", __func__, > > level, pte_paddr); > > - if (!pmap_extract(vcpu->vc_parent->vm_map->pmap, pte_paddr, > > + if (!pmap_extract(vcpu->vc_parent->vm_pmap, pte_paddr, > > &hpa)) { > > DPRINTF("%s: cannot extract HPA for GPA 0x%llx\n", > > __func__, pte_paddr); > > @@ -3694,11 +3660,11 @@ vcpu_run_vmx(struct vcpu *vcpu, struct vm_run_params * > > > > /* We're now using this vcpu's EPT pmap on this cpu. */ > > atomic_swap_ptr(&ci->ci_ept_pmap, > > - vcpu->vc_parent->vm_map->pmap); > > + vcpu->vc_parent->vm_pmap); > > > > /* Invalidate EPT cache. */ > > vid_ept.vid_reserved = 0; > > - vid_ept.vid_eptp = vcpu->vc_parent->vm_map->pmap->eptp; > > + vid_ept.vid_eptp = vcpu->vc_parent->vm_pmap->eptp; > > if (invept(ci->ci_vmm_cap.vcc_vmx.vmx_invept_mode, > > &vid_ept)) { > > printf("%s: invept\n", __func__); > > @@ -4484,6 +4450,29 @@ vmm_get_guest_memtype(struct vm *vm, paddr_t gpa) > > return (VMM_MEM_TYPE_UNKNOWN); > > } > > > > +vaddr_t > > +vmm_translate_gpa(struct vm *vm, paddr_t gpa) > > +{ > > + int i = 0; > > + vaddr_t hva = 0; > > + struct vm_mem_range *vmr = NULL; > > + > > + /* > > + * Translate GPA -> userland HVA in proc p. Find the memory range > > + * and use it to translate to the HVA. > > + */ > > + for (i = 0; i < vm->vm_nmemranges; i++) { > > + vmr = &vm->vm_memranges[i]; > > + if (gpa >= vmr->vmr_gpa && gpa < vmr->vmr_gpa + vmr->vmr_size) { > > + hva = vmr->vmr_va + (gpa - vmr->vmr_gpa); > > + break; > > + } > > + } > > + > > + return (hva); > > +} > > + > > + > > /* > > * vmx_get_exit_qualification > > * > > @@ -4565,15 +4554,45 @@ svm_get_guest_faulttype(struct vmcb *vmcb) > > int > > svm_fault_page(struct vcpu *vcpu, paddr_t gpa) > > { > > - paddr_t pa = trunc_page(gpa); > > - int ret; > > + struct proc *p = curproc; > > + paddr_t hpa, pa = trunc_page(gpa); > > + vaddr_t hva; > > + int ret = 1; > > > > - ret = uvm_fault_wire(vcpu->vc_parent->vm_map, pa, pa + PAGE_SIZE, > > - PROT_READ | PROT_WRITE | PROT_EXEC); > > - if (ret) > > - printf("%s: uvm_fault returns %d, GPA=0x%llx, rip=0x%llx\n", > > - __func__, ret, (uint64_t)gpa, vcpu->vc_gueststate.vg_rip); > > + hva = vmm_translate_gpa(vcpu->vc_parent, pa); > > + if (hva == 0) { > > + printf("%s: unable to translate gpa 0x%llx\n", __func__, > > + (uint64_t)pa); > > + return (EINVAL); > > + } > > > > + /* If we don't already have a backing page... */ > > + if (!pmap_extract(p->p_vmspace->vm_map.pmap, hva, &hpa)) { > > + /* ...fault a RW page into the p's address space... */ > > + ret = uvm_fault_wire(&p->p_vmspace->vm_map, hva, > > + hva + PAGE_SIZE, PROT_READ | PROT_WRITE); > > + if (ret) { > > + printf("%s: uvm_fault failed %d hva=0x%llx\n", __func__, > > + ret, (uint64_t)hva); > > + return (ret); > > + } > > + > > + /* ...and then get the mapping. */ > > + if (!pmap_extract(p->p_vmspace->vm_map.pmap, hva, &hpa)) { > > + printf("%s: failed to extract hpa for hva 0x%llx\n", > > + __func__, (uint64_t)hva); > > + return (EINVAL); > > + } > > + } > > + > > + /* Now we insert a RWX mapping into the guest's RVI pmap. */ > > + ret = pmap_enter(vcpu->vc_parent->vm_pmap, pa, hpa, > > + PROT_READ | PROT_WRITE | PROT_EXEC, 0); > > + if (ret) { > > + printf("%s: pmap_enter failed pa=0x%llx, hpa=0x%llx\n", > > + __func__, (uint64_t)pa, (uint64_t)hpa); > > + } > > + > > return (ret); > > } > > > > @@ -4640,8 +4659,10 @@ svm_handle_np_fault(struct vcpu *vcpu) > > int > > vmx_fault_page(struct vcpu *vcpu, paddr_t gpa) > > { > > + struct proc *p = curproc; > > int fault_type, ret; > > - paddr_t pa = trunc_page(gpa); > > + paddr_t hpa, pa = trunc_page(gpa); > > + vaddr_t hva; > > > > fault_type = vmx_get_guest_faulttype(); > > switch (fault_type) { > > @@ -4656,19 +4677,45 @@ vmx_fault_page(struct vcpu *vcpu, paddr_t gpa) > > break; > > } > > > > - /* We may sleep during uvm_fault_wire(), so reload VMCS. */ > > - vcpu->vc_last_pcpu = curcpu(); > > - ret = uvm_fault_wire(vcpu->vc_parent->vm_map, pa, pa + PAGE_SIZE, > > - PROT_READ | PROT_WRITE | PROT_EXEC); > > - if (vcpu_reload_vmcs_vmx(vcpu)) { > > - printf("%s: failed to reload vmcs\n", __func__); > > + hva = vmm_translate_gpa(vcpu->vc_parent, pa); > > + if (hva == 0) { > > + printf("%s: unable to translate gpa 0x%llx\n", __func__, > > + (uint64_t)pa); > > return (EINVAL); > > } > > > > - if (ret) > > - printf("%s: uvm_fault returns %d, GPA=0x%llx, rip=0x%llx\n", > > - __func__, ret, (uint64_t)gpa, vcpu->vc_gueststate.vg_rip); > > + /* If we don't already have a backing page... */ > > + if (!pmap_extract(p->p_vmspace->vm_map.pmap, hva, &hpa)) { > > + /* ...fault a RW page into the p's address space... */ > > + vcpu->vc_last_pcpu = curcpu(); /* uvm_fault may sleep. */ > > + ret = uvm_fault_wire(&p->p_vmspace->vm_map, hva, > > + hva + PAGE_SIZE, PROT_READ | PROT_WRITE); > > + if (ret) { > > + printf("%s: uvm_fault failed %d hva=0x%llx\n", __func__, > > + ret, (uint64_t)hva); > > + return (ret); > > + } > > + if (vcpu_reload_vmcs_vmx(vcpu)) { > > + printf("%s: failed to reload vmcs\n", __func__); > > + return (EINVAL); > > + } > > > > + /* ...and then get the mapping. */ > > + if (!pmap_extract(p->p_vmspace->vm_map.pmap, hva, &hpa)) { > > + printf("%s: failed to extract hpa for hva 0x%llx\n", > > + __func__, (uint64_t)hva); > > + return (EINVAL); > > + } > > + } > > + > > + /* Now we insert a RWX mapping into the guest's EPT pmap. */ > > + ret = pmap_enter(vcpu->vc_parent->vm_pmap, pa, hpa, > > + PROT_READ | PROT_WRITE | PROT_EXEC, 0); > > + if (ret) { > > + printf("%s: pmap_enter failed pa=0x%llx, hpa=0x%llx\n", > > + __func__, (uint64_t)pa, (uint64_t)hpa); > > + } > > + > > return (ret); > > } > > > > @@ -4953,7 +5000,7 @@ vmx_load_pdptes(struct vcpu *vcpu) > > return (EINVAL); > > } > > > > - if (!pmap_extract(vcpu->vc_parent->vm_map->pmap, (vaddr_t)cr3, > > + if (!pmap_extract(vcpu->vc_parent->vm_pmap, (vaddr_t)cr3, > > (paddr_t *)&cr3_host_phys)) { > > DPRINTF("%s: nonmapped guest CR3, setting PDPTEs to 0\n", > > __func__); > > @@ -6499,7 +6546,7 @@ vmm_update_pvclock(struct vcpu *vcpu) > > > > if (vcpu->vc_pvclock_system_gpa & PVCLOCK_SYSTEM_TIME_ENABLE) { > > pvclock_gpa = vcpu->vc_pvclock_system_gpa & 0xFFFFFFFFFFFFFFF0; > > - if (!pmap_extract(vm->vm_map->pmap, pvclock_gpa, &pvclock_hpa)) > > + if (!pmap_extract(vm->vm_pmap, pvclock_gpa, &pvclock_hpa)) > > return (EINVAL); > > pvclock_ti = (void*) PMAP_DIRECT_MAP(pvclock_hpa); > > > > blob - 0a86ddbecd3fbd3627336902c7209f6d023bc3f0 > > blob + 4d39ff3b6910e1b905c959476073eed89471f407 > > --- sys/dev/vmm/vmm.c > > +++ sys/dev/vmm/vmm.c > > @@ -25,6 +25,9 @@ > > #include > > #include > > > > +#include > > +#include > > + > > #include > > > > #include > > @@ -356,6 +359,9 @@ vm_create(struct vm_create_params *vcp, struct proc *p > > size_t memsize; > > struct vm *vm; > > struct vcpu *vcpu; > > + struct uvm_object *uao; > > + struct vm_mem_range *vmr; > > + unsigned int uvmflags = 0; > > > > memsize = vm_create_check_mem_ranges(vcp); > > if (memsize == 0) > > @@ -378,13 +384,61 @@ vm_create(struct vm_create_params *vcp, struct proc *p > > /* Instantiate and configure the new vm. */ > > vm = pool_get(&vm_pool, PR_WAITOK | PR_ZERO); > > > > + /* Create the VM's identity. */ > > vm->vm_creator_pid = p->p_p->ps_pid; > > + strncpy(vm->vm_name, vcp->vcp_name, VMM_MAX_NAME_LEN - 1); > > + > > + /* Create the pmap for nested paging. */ > > + vm->vm_pmap = pmap_create(); > > + > > + /* Initialize memory slots. */ > > vm->vm_nmemranges = vcp->vcp_nmemranges; > > memcpy(vm->vm_memranges, vcp->vcp_memranges, > > vm->vm_nmemranges * sizeof(vm->vm_memranges[0])); > > - vm->vm_memory_size = memsize; > > - strncpy(vm->vm_name, vcp->vcp_name, VMM_MAX_NAME_LEN - 1); > > + vm->vm_memory_size = memsize; /* Calculated above. */ > > > > + uvmflags = UVM_MAPFLAG(PROT_READ | PROT_WRITE, PROT_READ | PROT_WRITE, > > + MAP_INHERIT_NONE, MADV_NORMAL, UVM_FLAG_CONCEAL); > > + for (i = 0; i < vm->vm_nmemranges; i++) { > > + vmr = &vm->vm_memranges[i]; > > + if (vmr->vmr_type == VM_MEM_MMIO) > > + continue; > > + > > + uao = NULL; > > + uao = uao_create(vmr->vmr_size, UAO_FLAG_CANFAIL); > > + if (uao == NULL) { > > + printf("%s: failed to initialize memory slot\n", > > + __func__); > > + vm_teardown(&vm); > > + return (ENOMEM); > > + } > > + > > + /* Map the UVM aobj into the process. It owns this reference. */ > > + ret = uvm_map(&p->p_vmspace->vm_map, &vmr->vmr_va, > > + vmr->vmr_size, uao, 0, 0, uvmflags); > > + if (ret) { > > + printf("%s: uvm_map failed: %d\n", __func__, ret); > > + uao_detach(uao); > > + vm_teardown(&vm); > > + return (ENOMEM); > > + } > > + > > + /* Make this mapping immutable so userland cannot change it. */ > > + ret = uvm_map_immutable(&p->p_vmspace->vm_map, vmr->vmr_va, > > + vmr->vmr_va + vmr->vmr_size, 1); > > + if (ret) { > > + printf("%s: uvm_map_immutable failed: %d\n", __func__, > > + ret); > > + uvm_unmap(&p->p_vmspace->vm_map, vmr->vmr_va, > > + vmr->vmr_va + vmr->vmr_size); > > + vm_teardown(&vm); > > + return (ret); > > + } > > + > > + uao_reference(uao); /* Take a reference for vmm. */ > > + vm->vm_memory_slot[i] = uao; > > + } > > + > > if (vm_impl_init(vm, p)) { > > printf("failed to init arch-specific features for vm %p\n", vm); > > vm_teardown(&vm); > > @@ -433,6 +487,10 @@ vm_create(struct vm_create_params *vcp, struct proc *p > > vmm_softc->vm_ct++; > > vmm_softc->vcpu_ct += vm->vm_vcpu_ct; > > > > + /* Update the userland process's view of guest memory. */ > > + memcpy(vcp->vcp_memranges, vm->vm_memranges, > > + vcp->vcp_nmemranges * sizeof(vcp->vcp_memranges[0])); > > + > > rw_exit_write(&vmm_softc->vm_lock); > > > > return (0); > > @@ -482,19 +540,6 @@ vm_create_check_mem_ranges(struct vm_create_params *vc > > } > > > > /* > > - * Make sure that all virtual addresses are within the address > > - * space of the process and that they do not wrap around. > > - * Calling uvm_share() when creating the VM will take care of > > - * further checks. > > - */ > > - if (vmr->vmr_va < VM_MIN_ADDRESS || > > - vmr->vmr_va >= VM_MAXUSER_ADDRESS || > > - vmr->vmr_size >= VM_MAXUSER_ADDRESS - vmr->vmr_va) { > > - DPRINTF("guest va not within range or wraps\n"); > > - return (0); > > - } > > - > > - /* > > * Make sure that guest physical memory ranges do not overlap > > * and that they are ascending. > > */ > > @@ -529,10 +574,11 @@ vm_create_check_mem_ranges(struct vm_create_params *vc > > void > > vm_teardown(struct vm **target) > > { > > - size_t nvcpu = 0; > > + size_t i, nvcpu = 0; > > + vaddr_t sva, eva; > > struct vcpu *vcpu, *tmp; > > struct vm *vm = *target; > > - struct vmspace *vm_vmspace; > > + struct uvm_object *uao; > > > > KERNEL_ASSERT_UNLOCKED(); > > > > @@ -540,22 +586,29 @@ vm_teardown(struct vm **target) > > SLIST_FOREACH_SAFE(vcpu, &vm->vm_vcpu_list, vc_vcpu_link, tmp) { > > SLIST_REMOVE(&vm->vm_vcpu_list, vcpu, vcpu, vc_vcpu_link); > > vcpu_deinit(vcpu); > > - > > pool_put(&vcpu_pool, vcpu); > > nvcpu++; > > } > > > > - vm_impl_deinit(vm); > > + /* Remove guest mappings from our nested page tables. */ > > + for (i = 0; i < vm->vm_nmemranges; i++) { > > + sva = vm->vm_memranges[i].vmr_gpa; > > + eva = sva + vm->vm_memranges[i].vmr_size - 1; > > + pmap_remove(vm->vm_pmap, sva, eva); > > + } > > > > - /* teardown guest vmspace */ > > - KERNEL_LOCK(); > > - vm_vmspace = vm->vm_vmspace; > > - if (vm_vmspace != NULL) { > > - vm->vm_vmspace = NULL; > > - uvmspace_free(vm_vmspace); > > + /* Release UVM anon objects backing our guest memory. */ > > + for (i = 0; i < vm->vm_nmemranges; i++) { > > + uao = vm->vm_memory_slot[i]; > > + vm->vm_memory_slot[i] = NULL; > > + if (uao != NULL) > > + uao_detach(uao); > > } > > - KERNEL_UNLOCK(); > > > > + /* At this point, no UVM-managed pages should reference our pmap. */ > > + pmap_destroy(vm->vm_pmap); > > + vm->vm_pmap = NULL; > > + > > pool_put(&vm_pool, vm); > > *target = NULL; > > } > > @@ -612,7 +665,7 @@ vm_get_info(struct vm_info_params *vip) > > > > out[i].vir_memory_size = vm->vm_memory_size; > > out[i].vir_used_size = > > - pmap_resident_count(vm->vm_map->pmap) * PAGE_SIZE; > > + pmap_resident_count(vm->vm_pmap) * PAGE_SIZE; > > out[i].vir_ncpus = vm->vm_vcpu_ct; > > out[i].vir_id = vm->vm_id; > > out[i].vir_creator_pid = vm->vm_creator_pid; > > @@ -793,17 +846,17 @@ vcpu_must_stop(struct vcpu *vcpu) > > * Return values: > > * 0: if successful > > * ENOENT: if the vm cannot be found by vm_find > > - * EPERM: if the vm cannot be accessed by the current process > > - * EINVAL: if the provide memory ranges fail checks > > - * ENOMEM: if uvm_share fails to find available memory in the destination map > > + * other errno on uvm_map or uvm_map_immutable failures > > */ > > int > > vm_share_mem(struct vm_sharemem_params *vsp, struct proc *p) > > { > > - int ret = EINVAL; > > - size_t i, n; > > + int ret = EINVAL, unmap = 0; > > + size_t i, failed_uao = 0, n; > > struct vm *vm; > > struct vm_mem_range *src, *dst; > > + struct uvm_object *uao; > > + unsigned int uvmflags; > > > > ret = vm_find(vsp->vsp_vm_id, &vm); > > if (ret) > > @@ -830,36 +883,52 @@ vm_share_mem(struct vm_sharemem_params *vsp, struct pr > > if (src->vmr_size != dst->vmr_size) > > goto out; > > > > - /* Check our intended destination is page-aligned. */ > > - if (dst->vmr_va & PAGE_MASK) > > + /* The virtual addresses will be chosen by uvm_map(). */ > > + if (vsp->vsp_va[i] != 0) > > goto out; > > } > > > > - /* > > - * Share each range individually with the calling process. We do > > - * not need PROC_EXEC as the emulated devices do not need to execute > > - * instructions from guest memory. > > - */ > > + /* Share each UVM aobj with the calling process. */ > > + uvmflags = UVM_MAPFLAG(PROT_READ | PROT_WRITE, PROT_READ | PROT_WRITE, > > + MAP_INHERIT_NONE, MADV_NORMAL, UVM_FLAG_CONCEAL); > > for (i = 0; i < n; i++) { > > - src = &vm->vm_memranges[i]; > > dst = &vsp->vsp_memranges[i]; > > - > > - /* Skip MMIO range. */ > > - if (src->vmr_type == VM_MEM_MMIO) > > + if (dst->vmr_type == VM_MEM_MMIO) > > continue; > > > > - DPRINTF("sharing gpa=0x%lx for pid %d @ va=0x%lx\n", > > - src->vmr_gpa, p->p_p->ps_pid, dst->vmr_va); > > - ret = uvm_share(&p->p_vmspace->vm_map, dst->vmr_va, > > - PROT_READ | PROT_WRITE, vm->vm_map, src->vmr_gpa, > > - src->vmr_size); > > + uao = vm->vm_memory_slot[i]; > > + KASSERT(uao != NULL); > > + > > + ret = uvm_map(&p->p_p->ps_vmspace->vm_map, &vsp->vsp_va[i], > > + dst->vmr_size, uao, 0, 0, uvmflags); > > if (ret) { > > - printf("%s: uvm_share failed (%d)\n", __func__, ret); > > - break; > > + printf("%s: uvm_map failed: %d\n", __func__, ret); > > + unmap = (i > 0) ? 1 : 0; > > + failed_uao = i; > > + goto out; > > } > > + uao_reference(uao); /* Add a reference for the process. */ > > + > > + ret = uvm_map_immutable(&p->p_p->ps_vmspace->vm_map, > > + vsp->vsp_va[i], vsp->vsp_va[i] + dst->vmr_size, 1); > > + if (ret) { > > + printf("%s: uvm_map_immutable failed: %d\n", > > + __func__, ret); > > + unmap = 1; > > + failed_uao = i + 1; > > + goto out; > > + } > > } > > ret = 0; > > out: > > + if (unmap) { > > + /* Unmap mapped aobjs, which drops the process's reference. */ > > + for (i = 0; i < failed_uao; i++) { > > + dst = &vsp->vsp_memranges[i]; > > + uvm_unmap(&p->p_p->ps_vmspace->vm_map, > > + vsp->vsp_va[i], vsp->vsp_va[i] + dst->vmr_size); > > + } > > + } > > refcnt_rele_wake(&vm->vm_refcnt); > > return (ret); > > } > > blob - 621dd08080c5f40e4b594737b4ea68f1ce98d5d1 > > blob + 78d0681cda32a01b11914fd55315230f817c64a5 > > --- sys/dev/vmm/vmm.h > > +++ sys/dev/vmm/vmm.h > > @@ -95,6 +95,9 @@ struct vm_sharemem_params { > > uint32_t vsp_vm_id; > > size_t vsp_nmemranges; > > struct vm_mem_range vsp_memranges[VMM_MAX_MEM_RANGES]; > > + > > + /* Output parameters from VMM_IOC_SHAREMEM */ > > + vaddr_t vsp_va[VMM_MAX_MEM_RANGES]; > > }; > > > > struct vm_run_params { > > @@ -138,7 +141,7 @@ struct vm_rwvmparams_params { > > #define VMM_IOC_READVMPARAMS _IOWR('V', 9, struct vm_rwvmparams_params) > > /* Set VM params */ > > #define VMM_IOC_WRITEVMPARAMS _IOW('V', 10, struct vm_rwvmparams_params) > > -#define VMM_IOC_SHAREMEM _IOW('V', 11, struct vm_sharemem_params) > > +#define VMM_IOC_SHAREMEM _IOWR('V', 11, struct vm_sharemem_params) > > > > #ifdef _KERNEL > > > > @@ -169,14 +172,17 @@ enum { > > * V vmm_softc's vm_lock > > */ > > struct vm { > > - struct vmspace *vm_vmspace; /* [K] */ > > - vm_map_t vm_map; /* [K] */ > > + pmap_t vm_pmap; /* [r] */ > > + > > uint32_t vm_id; /* [I] */ > > pid_t vm_creator_pid; /* [I] */ > > + > > size_t vm_nmemranges; /* [I] */ > > size_t vm_memory_size; /* [I] */ > > - char vm_name[VMM_MAX_NAME_LEN]; > > struct vm_mem_range vm_memranges[VMM_MAX_MEM_RANGES]; > > + struct uvm_object *vm_memory_slot[VMM_MAX_MEM_RANGES]; /* [I] */ > > + > > + char vm_name[VMM_MAX_NAME_LEN]; > > struct refcnt vm_refcnt; /* [a] */ > > > > struct vcpu_head vm_vcpu_list; /* [v] */ > > blob - e399c0c0439a02117bc53c62cbb59c950b176773 > > blob + 30b12b0e30936bddf75484aeedf60a34b1296d89 > > --- usr.sbin/vmd/vm.c > > +++ usr.sbin/vmd/vm.c > > @@ -49,7 +49,6 @@ static void vm_dispatch_vmm(int, short, void *); > > static void *event_thread(void *); > > static void *vcpu_run_loop(void *); > > static int vmm_create_vm(struct vmd_vm *); > > -static int alloc_guest_mem(struct vmd_vm *); > > static int send_vm(int, struct vmd_vm *); > > static int dump_vmr(int , struct vm_mem_range *); > > static int dump_mem(int, struct vmd_vm *); > > @@ -201,7 +200,8 @@ start_vm(struct vmd_vm *vm, int fd) > > if (!(vm->vm_state & VM_STATE_RECEIVED)) > > create_memory_map(vcp); > > > > - ret = alloc_guest_mem(vm); > > + /* Create the vm in vmm(4). */ > > + ret = vmm_create_vm(vm); > > if (ret) { > > struct rlimit lim; > > char buf[FMT_SCALED_STRSIZE]; > > @@ -209,15 +209,11 @@ start_vm(struct vmd_vm *vm, int fd) > > if (fmt_scaled(lim.rlim_cur, buf) == 0) > > fatalx("could not allocate guest memory (data " > > "limit is %s)", buf); > > + } else { > > + errno = ret; > > + log_warn("could not create vm"); > > } > > - errno = ret; > > - log_warn("could not allocate guest memory"); > > - return (ret); > > - } > > > > - /* We've allocated guest memory, so now create the vm in vmm(4). */ > > - ret = vmm_create_vm(vm); > > - if (ret) { > > /* Let the vmm process know we failed by sending a 0 vm id. */ > > vcp->vcp_id = 0; > > atomicio(vwrite, fd, &vcp->vcp_id, sizeof(vcp->vcp_id)); > > @@ -756,62 +752,6 @@ vcpu_reset(uint32_t vmid, uint32_t vcpu_id, struct vcp > > } > > > > /* > > - * alloc_guest_mem > > - * > > - * Allocates memory for the guest. > > - * Instead of doing a single allocation with one mmap(), we allocate memory > > - * separately for every range for the following reasons: > > - * - ASLR for the individual ranges > > - * - to reduce memory consumption in the UVM subsystem: if vmm(4) had to > > - * map the single mmap'd userspace memory to the individual guest physical > > - * memory ranges, the underlying amap of the single mmap'd range would have > > - * to allocate per-page reference counters. The reason is that the > > - * individual guest physical ranges would reference the single mmap'd region > > - * only partially. However, if every guest physical range has its own > > - * corresponding mmap'd userspace allocation, there are no partial > > - * references: every guest physical range fully references an mmap'd > > - * range => no per-page reference counters have to be allocated. > > - * > > - * Return values: > > - * 0: success > > - * !0: failure - errno indicating the source of the failure > > - */ > > -int > > -alloc_guest_mem(struct vmd_vm *vm) > > -{ > > - void *p; > > - int ret = 0; > > - size_t i, j; > > - struct vm_create_params *vcp = &vm->vm_params.vmc_params; > > - struct vm_mem_range *vmr; > > - > > - for (i = 0; i < vcp->vcp_nmemranges; i++) { > > - vmr = &vcp->vcp_memranges[i]; > > - > > - /* > > - * We only need R/W as userland. vmm(4) will use R/W/X in its > > - * mapping. > > - * > > - * We must use MAP_SHARED so emulated devices will be able > > - * to generate shared mappings. > > - */ > > - p = mmap(NULL, vmr->vmr_size, PROT_READ | PROT_WRITE, > > - MAP_ANON | MAP_CONCEAL | MAP_SHARED, -1, 0); > > - if (p == MAP_FAILED) { > > - ret = errno; > > - for (j = 0; j < i; j++) { > > - vmr = &vcp->vcp_memranges[j]; > > - munmap((void *)vmr->vmr_va, vmr->vmr_size); > > - } > > - return (ret); > > - } > > - vmr->vmr_va = (vaddr_t)p; > > - } > > - > > - return (ret); > > -} > > - > > -/* > > * vmm_create_vm > > * > > * Requests vmm(4) to create a new VM using the supplied creation > > @@ -1384,87 +1324,35 @@ vm_pipe_recv(struct vm_dev_pipe *p) > > } > > > > /* > > - * Re-map the guest address space using vmm(4)'s VMM_IOC_SHARE > > + * Re-map the guest address space using vmm(4)'s VMM_IOC_SHAREMEM > > * > > - * Returns 0 on success, non-zero in event of failure. > > + * Returns 0 on success or an errno in event of failure. > > */ > > int > > remap_guest_mem(struct vmd_vm *vm, int vmm_fd) > > { > > - struct vm_create_params *vcp; > > - struct vm_mem_range *vmr; > > + size_t i; > > + struct vm_create_params *vcp = &vm->vm_params.vmc_params; > > struct vm_sharemem_params vsp; > > - size_t i, j; > > - void *p = NULL; > > - int ret; > > > > if (vm == NULL) > > - return (1); > > + return (EINVAL); > > > > - vcp = &vm->vm_params.vmc_params; > > - > > - /* > > - * Initialize our VM shared memory request using our original > > - * creation parameters. We'll overwrite the va's after mmap(2). > > - */ > > + /* Initialize using our original creation parameters. */ > > memset(&vsp, 0, sizeof(vsp)); > > vsp.vsp_nmemranges = vcp->vcp_nmemranges; > > vsp.vsp_vm_id = vcp->vcp_id; > > memcpy(&vsp.vsp_memranges, &vcp->vcp_memranges, > > sizeof(vsp.vsp_memranges)); > > > > - /* > > - * Use mmap(2) to identify virtual address space for our mappings. > > - */ > > - for (i = 0; i < VMM_MAX_MEM_RANGES; i++) { > > - if (i < vsp.vsp_nmemranges) { > > - vmr = &vsp.vsp_memranges[i]; > > - > > - /* Ignore any MMIO ranges. */ > > - if (vmr->vmr_type == VM_MEM_MMIO) { > > - vmr->vmr_va = 0; > > - vcp->vcp_memranges[i].vmr_va = 0; > > - continue; > > - } > > - > > - /* Make initial mappings for the memrange. */ > > - p = mmap(NULL, vmr->vmr_size, PROT_READ, MAP_ANON, -1, > > - 0); > > - if (p == MAP_FAILED) { > > - ret = errno; > > - log_warn("%s: mmap", __func__); > > - for (j = 0; j < i; j++) { > > - vmr = &vcp->vcp_memranges[j]; > > - munmap((void *)vmr->vmr_va, > > - vmr->vmr_size); > > - } > > - return (ret); > > - } > > - vmr->vmr_va = (vaddr_t)p; > > - vcp->vcp_memranges[i].vmr_va = vmr->vmr_va; > > - } > > - } > > - > > - /* > > - * munmap(2) now that we have va's and ranges that don't overlap. vmm > > - * will use the va's and sizes to recreate the mappings for us. > > - */ > > - for (i = 0; i < vsp.vsp_nmemranges; i++) { > > - vmr = &vsp.vsp_memranges[i]; > > - if (vmr->vmr_type == VM_MEM_MMIO) > > - continue; > > - if (munmap((void*)vmr->vmr_va, vmr->vmr_size) == -1) > > - fatal("%s: munmap", __func__); > > - } > > - > > - /* > > - * Ask vmm to enter the shared mappings for us. They'll point > > - * to the same host physical memory, but will have a randomized > > - * virtual address for the calling process. > > - */ > > + /* Ask vmm(4) to enter a shared mapping to guest memory. */ > > if (ioctl(vmm_fd, VMM_IOC_SHAREMEM, &vsp) == -1) > > return (errno); > > > > + /* Update with the location of the new mappings. */ > > + for (i = 0; i < vsp.vsp_nmemranges; i++) > > + vcp->vcp_memranges[i].vmr_va = vsp.vsp_va[i]; > > + > > return (0); > > } > > > > -- > Dr. Hans-Jörg Höxer Hans-Joerg_Hoexer@genua.de > Senior Expert Kryptographie > eXtreme Kernel and Crypto Development > > genua GmbH > Domagkstrasse 7, 85551 Kirchheim bei München > tel +49 89 991950-0, fax -999, www.genua.eu > > Geschäftsführer: Matthias Ochs, Marc Tesch > Amtsgericht München HRB 98238 > genua ist ein Unternehmen der Bundesdruckerei-Gruppe. > > > > > > > Julia Template > > Betreff : Re: [EXT] Re: Reworking VMM's nested paging & guest memory (de-vmspace-ification) > Sender : owner-tech+M103328=hshoexer=genua.de@openbsd.org > Envelope Sender : owner-tech+M103328=hshoexer=genua.de@openbsd.org > Sender Name : Hans-Jörg Höxer > Sender Domain : openbsd.org > Message ID : > Mail Size : 44172 > Time : 13.05.2025 15:42:51 (Di 13 Mai 2025 15:42:51 CEST) > Julia Commands : Keine Kommandos verwendet > > Die Nachricht war signiert. > > Allgemeine Informationen zur Signatur: > Die Signatur der Nachricht war gültig. > Der Nachrichtenumschlag war S/MIME signiert. > > S/MIME-Engine Antworten: > Envelope Signer : /C=DE/O=genua GmbH/CN=Hans-J\xC3\xB6rg H\xC3\xB6xer/L=Kirchheim b. M\xC3\xBCnchen/GN=Hans-J\xC3\xB6rg/SN=H\xC3\xB6xer/organizationIdentifier=NTRDE-D2601V.HRB98238/serialNumber=CSM043478563/ST=Bayern > > Info Signatur : CMS Inhaltstyp : pkcs7-signedData (1.2.840.113549.1.7.2) > Verschlüsselter Content-Type : pkcs7-data (1.2.840.113549.1.7.1) > Signatur Zertifikat Fingerprint SHA1: 8A:6A:1A:A3:1A:B4:EA:25:18:45:2E:6E:E2:CE:DC:64:F0:3D:9B:26 > Signatur Zertifikat Schlüssellänge: 4096 (RSA) > Signatur Zertifikat Seriennummer: 74:36:DA:14:8D:EC:3B:D4:F6:35:7A:F3:88:82:CB:FE > Signatur Zertifikat gültig ab: Sep 17 14:21:48 2024 GMT > Signatur Zertifikat gültig bis: Sep 20 14:21:48 2025 GMT > Signatur Zertifikat gültig für die Verschlüsselung: Ja > Signatur Zertifikat gültig für die Signatur: Ja > Signatur Zertifikats CA /C=DE/O=D-Trust GmbH/CN=D-TRUST Application Certificates CA 3-1 2013 > Signatur MD : sha256 (2.16.840.1.101.3.4.2.1) > Signaturalgorithmus : rsaEncryption (1.2.840.113549.1.1.1) > Signaturzeitpunkt: May 13 13:42:10 2025 GMT > Signaturzertifikat enthält nicht die Email-Adresse des Absenders 'owner-tech+M103328=hshoexer=genua.de@openbsd.org' > > MD Signatur : : sha256 (2.16.840.1.101.3.4.2.1) > > Signature Engine Response : > Verify Engine Response : > Verification OK (0) > > Qualified Verify Engine Response : > > > > > > > > Ende des Julia-Templates -- Dr. Hans-Jörg Höxer Hans-Joerg_Hoexer@genua.de Senior Expert Kryptographie eXtreme Kernel and Crypto Development genua GmbH Domagkstrasse 7, 85551 Kirchheim bei München tel +49 89 991950-0, fax -999, www.genua.eu Geschäftsführer: Matthias Ochs, Marc Tesch Amtsgericht München HRB 98238 genua ist ein Unternehmen der Bundesdruckerei-Gruppe.