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SEV-ES guest: locore #VC trap handling
Hi Mike,
I have commited the locore0 guest part of the #VC trap handler.
Let's see if there is any fallout.
The part below for vmd(8) is still missing. Can you have a look?
bluhm
On Wed, May 21, 2025 at 05:10:27PM +0200, Hans-J?rg H?xer wrote:
> commit c29b30056940a3f8b2acfd18b734daf60257656a
> Author: Hans-Joerg Hoexer <hshoexer@genua.de>
> Date: Wed Nov 20 11:16:48 2024 +0100
>
> vmd(8): Setup long mode code segment for SEV-ES guests
>
> Right now vmd(8) starts a kernel image in compatibility mode.
> However, SEV-ES enabled guest will trigger #VC traps during locore.
> To be able to run such a trap handler, we need a long mode segment.
>
> diff --git a/usr.sbin/vmd/loadfile_elf.c b/usr.sbin/vmd/loadfile_elf.c
> index 2b62ca07565..73c2010397d 100644
> --- a/usr.sbin/vmd/loadfile_elf.c
> +++ b/usr.sbin/vmd/loadfile_elf.c
> @@ -110,7 +110,7 @@ union {
> } hdr;
>
> static void setsegment(struct mem_segment_descriptor *, uint32_t,
> - size_t, int, int, int, int);
> + size_t, int, int, int, int, int);
> static int elf32_exec(gzFile, Elf32_Ehdr *, u_long *, int);
> static int elf64_exec(gzFile, Elf64_Ehdr *, u_long *, int);
> static size_t create_bios_memmap(struct vm_create_params *, bios_memmap_t *);
> @@ -148,7 +148,7 @@ uint64_t pg_crypt = 0;
> */
> static void
> setsegment(struct mem_segment_descriptor *sd, uint32_t base, size_t limit,
> - int type, int dpl, int def32, int gran)
> + int type, int dpl, int def32, int gran, int lm)
> {
> sd->sd_lolimit = (int)limit;
> sd->sd_lobase = (int)base;
> @@ -157,7 +157,7 @@ setsegment(struct mem_segment_descriptor *sd, uint32_t base, size_t limit,
> sd->sd_p = 1;
> sd->sd_hilimit = (int)limit >> 16;
> sd->sd_avl = 0;
> - sd->sd_long = 0;
> + sd->sd_long = lm;
> sd->sd_def32 = def32;
> sd->sd_gran = gran;
> sd->sd_hibase = (int)base >> 24;
> @@ -185,11 +185,13 @@ push_gdt(void)
> * Create three segment descriptors:
> *
> * GDT[0] : null descriptor. "Created" via memset above.
> - * GDT[1] (selector @ 0x8): Executable segment, for CS
> + * GDT[1] (selector @ 0x8): Executable segment (compat mode), for CS
> * GDT[2] (selector @ 0x10): RW Data segment, for DS/ES/SS
> + * GDT[3] (selector @ 0x18): Executable segment (long mode), for CS
> */
> - setsegment(&sd[1], 0, 0xffffffff, SDT_MEMERA, SEL_KPL, 1, 1);
> - setsegment(&sd[2], 0, 0xffffffff, SDT_MEMRWA, SEL_KPL, 1, 1);
> + setsegment(&sd[1], 0, 0xffffffff, SDT_MEMERA, SEL_KPL, 1, 1, 0);
> + setsegment(&sd[2], 0, 0xffffffff, SDT_MEMRWA, SEL_KPL, 1, 1, 0);
> + setsegment(&sd[3], 0, 0xffffffff, SDT_MEMERA, SEL_KPL, 0, 1, 1);
>
> write_mem(GDT_PAGE, gdtpage, PAGE_SIZE);
> sev_register_encryption(GDT_PAGE, PAGE_SIZE);
SEV-ES guest: locore #VC trap handling