intel_iommu: Enable Enhanced Set Root Table Pointer Support (ESRTPS)

According to VTD spec rev 4.1 section 6.6:
"For implementations reporting the Enhanced Set Root Table Pointer Support
(ESRTPS) field as Clear, on a 'Set Root Table Pointer' operation, software
must perform a global invalidate of the context cache, PASID-cache (if
applicable), and IOTLB, in that order. This is required to ensure hardware
references only the remapping structures referenced by the new root table
pointer and not stale cached entries.

For implementations reporting the Enhanced Set Root Table Pointer Support
(ESRTPS) field as Set, as part of 'Set Root Table Pointer' operation,
hardware performs global invalidation on all DMA remapping translation
caches and hence software is not required to perform additional
invalidations"

We already implemented ESRTPS capability in vtd_handle_gcmd_srtp() by
calling vtd_reset_caches(), just set ESRTPS in DMAR_CAP_REG to avoid
unnecessary global invalidation requests of context, PASID-cache and
IOTLB from guest.

This change doesn't impact migration as the content of DMAR_CAP_REG is
migrated too.

Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Clément Mathieu--Drif <clement.mathieu--drif@eviden.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Message-ID: <20250929034206.439266-2-zhenzhong.duan@intel.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index fa2ad9c2eb01d40c92e1957687e0a37d837fd2e9..03785510387125204774c5925c180e408bdb36a3 100644 (file)
--- a/hw/i386/intel_iommu.c
+++ b/hw/i386/intel_iommu.c
@@ -4660,7 +4660,7 @@ static void vtd_cap_init(IntelIOMMUState *s)
 
     s->cap = VTD_CAP_FRO | VTD_CAP_NFR | VTD_CAP_ND |
              VTD_CAP_MAMV | VTD_CAP_PSI | VTD_CAP_SLLPS |
-             VTD_CAP_MGAW(s->aw_bits);
+             VTD_CAP_ESRTPS | VTD_CAP_MGAW(s->aw_bits);
     if (s->dma_drain) {
         s->cap |= VTD_CAP_DRAIN;
     }

diff --git a/hw/i386/intel_iommu_internal.h b/hw/i386/intel_iommu_internal.h
index 0d0069a612533e98a82d12d96a181b9e2ccd920c..0f6a1237e4cf89569fd889f2011e963ae45d889e 100644 (file)
--- a/hw/i386/intel_iommu_internal.h
+++ b/hw/i386/intel_iommu_internal.h
@@ -215,6 +215,7 @@
 #define VTD_CAP_DRAIN_WRITE         (1ULL << 54)
 #define VTD_CAP_DRAIN_READ          (1ULL << 55)
 #define VTD_CAP_FS1GP               (1ULL << 56)
+#define VTD_CAP_ESRTPS              (1ULL << 63)
 #define VTD_CAP_DRAIN               (VTD_CAP_DRAIN_READ | VTD_CAP_DRAIN_WRITE)
 #define VTD_CAP_CM                  (1ULL << 7)
 #define VTD_PASID_ID_SHIFT          20