SVM in Linux requires SMPWC. This is free in the current implementation
as it is already in line with the expected behaviour.
Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=780dfed68862
Fixes: 952e1a6e90eb ("intel_iommu: Add a CLI option to enable SVM")
Signed-off-by: Clement Mathieu--Drif <clement.mathieu--drif@bull.com>
---
Changes v1 -> v2:
- Check that host IOMMU also has the capability when accel is enabled
- Add link to the kernel commit that makes SMPWC mandatory
- Add a fix tag
---
hw/i386/intel_iommu.c | 3 ++-
hw/i386/intel_iommu_accel.c | 6 ++++++
hw/i386/intel_iommu_internal.h | 1 +
3 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index 8245452d89..9f21622a4f 100644
--- a/hw/i386/intel_iommu.c
+++ b/hw/i386/intel_iommu.c
@@ -5108,7 +5108,8 @@ static void vtd_init(IntelIOMMUState *s)
}
if (s->svm) {
- s->ecap |= VTD_ECAP_PRS | VTD_ECAP_PDS | VTD_ECAP_NWFS;
+ s->ecap |= VTD_ECAP_PRS | VTD_ECAP_PDS | VTD_ECAP_NWFS |
+ VTD_ECAP_SMPWCS;
}
vtd_reset_caches(s);
diff --git a/hw/i386/intel_iommu_accel.c b/hw/i386/intel_iommu_accel.c
index c03435f8a2..c3677775e9 100644
--- a/hw/i386/intel_iommu_accel.c
+++ b/hw/i386/intel_iommu_accel.c
@@ -37,6 +37,12 @@ bool vtd_check_hiod_accel(IntelIOMMUState *s, VTDHostIOMMUDevice *vtd_hiod,
return false;
}
+ if ((s->ecap & VTD_ECAP_SMPWCS) && !(vtd->ecap_reg & VTD_ECAP_SMPWCS)) {
+ error_setg(errp,
+ "Scalable-mode coherent walk is unsupported by host IOMMU");
+ return false;
+ }
+
if (s->fs1gp && !(vtd->cap_reg & VTD_CAP_FS1GP)) {
error_setg(errp,
"First stage 1GB large page is unsupported by host IOMMU");
diff --git a/hw/i386/intel_iommu_internal.h b/hw/i386/intel_iommu_internal.h
index 924e91cb8a..df7a0efa6e 100644
--- a/hw/i386/intel_iommu_internal.h
+++ b/hw/i386/intel_iommu_internal.h
@@ -202,6 +202,7 @@
#define VTD_ECAP_SMTS (1ULL << 43)
#define VTD_ECAP_SSTS (1ULL << 46)
#define VTD_ECAP_FSTS (1ULL << 47)
+#define VTD_ECAP_SMPWCS (1ULL << 48)
/* CAP_REG */
/* (offset >> 4) << 24 */
--
2.54.0