From: Patrick Wildt <patrick@blueri.se>
Subject: SMMUv3 tests
To: tech@openbsd.org
Date: Sun, 21 Sep 2025 10:40:59 +0200

Hi,

I'd like to get some more testing done on the initial SMMUv3 support
that's in the tree.  I've mostly been testing on the Rockchip RK3588
but I think this should also affect e.g. Ampere Altra-based systems?

Please give this diff a go on newer Arm-based machines and check if a
new smmu device pops up in dmesg, and if it does, if your I/O devices
still perform the same (or better or worse).

On Apple devices this diff won't make a difference, on those we have
apldart(4).

On QC machines this diff might make the driver try to attach in ACPI
mode; and possibly panic.  Reports on booting this diff in ACPI mode
would be highly appreciated.  In FDT mode this should not attach.

On Ampere Altra I'm expecting it to attach -- and hopefully work fine.

Cheers,
Patrick

diff --git a/sys/arch/arm64/dev/smmu.c b/sys/arch/arm64/dev/smmu.c
index f57796fdb97..fafbe3189b5 100644
--- a/sys/arch/arm64/dev/smmu.c
+++ b/sys/arch/arm64/dev/smmu.c
@@ -575,7 +575,6 @@ smmu_device_map(void *cookie, uint32_t sid, bus_dma_tag_t dmat)
 		dom->sd_dmat->_dmamap_load_uio = smmu_dmamap_load_uio;
 		dom->sd_dmat->_dmamap_load_raw = smmu_dmamap_load_raw;
 		dom->sd_dmat->_dmamap_unload = smmu_dmamap_unload;
-		dom->sd_dmat->_flags |= BUS_DMA_COHERENT;
 	}
 
 	return dom->sd_dmat;
diff --git a/sys/arch/arm64/dev/smmu_acpi.c b/sys/arch/arm64/dev/smmu_acpi.c
index 7d9206d5afb..718c13b04b0 100644
--- a/sys/arch/arm64/dev/smmu_acpi.c
+++ b/sys/arch/arm64/dev/smmu_acpi.c
@@ -66,7 +66,8 @@ smmu_acpi_match(struct device *parent, void *match, void *aux)
 	struct acpiiort_attach_args *aia = aux;
 	struct acpi_iort_node *node = aia->aia_node;
 
-	if (node->type != ACPI_IORT_SMMU)
+	if (node->type != ACPI_IORT_SMMU &&
+	    node->type != ACPI_IORT_SMMU_V3)
 		return 0;
 
 	return 1;
diff --git a/sys/arch/arm64/dev/smmu_fdt.c b/sys/arch/arm64/dev/smmu_fdt.c
index ee915e7f0dd..77bc7132055 100644
--- a/sys/arch/arm64/dev/smmu_fdt.c
+++ b/sys/arch/arm64/dev/smmu_fdt.c
@@ -69,8 +69,9 @@ smmu_fdt_match(struct device *parent, void *match, void *aux)
 {
 	struct fdt_attach_args *faa = aux;
 
-	return (OF_is_compatible(faa->fa_node, "arm,smmu-v2") ||
-	    OF_is_compatible(faa->fa_node, "arm,mmu-500"));
+	return (OF_is_compatible(faa->fa_node, "arm,mmu-500") ||
+	    OF_is_compatible(faa->fa_node, "arm,smmu-v2") ||
+	    OF_is_compatible(faa->fa_node, "arm,smmu-v3"));
 }
 
 void