On 2022/4/22 10:47, Tian, Kevin wrote:
From: Lu Baolu
Sent: Thursday, April 21, 2022 7:36 PM
The latest VT-d specification states that the PGSNP field in the pasid
table entry should be treated as Reserved(0) for implementations not
supporting Snoop Control (SC=0 in the Extended Capability Register).
This adds a check before setting the field.
Signed-off-by: Lu Baolu<[email protected]>
---
drivers/iommu/intel/pasid.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/drivers/iommu/intel/pasid.c b/drivers/iommu/intel/pasid.c
index f8d215d85695..5cb2daa2b8cb 100644
--- a/drivers/iommu/intel/pasid.c
+++ b/drivers/iommu/intel/pasid.c
@@ -625,8 +625,14 @@ int intel_pasid_setup_first_level(struct intel_iommu
*iommu,
}
}
- if (flags & PASID_FLAG_PAGE_SNOOP)
- pasid_set_pgsnp(pte);
+ if (flags & PASID_FLAG_PAGE_SNOOP) {
+ if (ecap_sc_support(iommu->ecap)) {
+ pasid_set_pgsnp(pte);
+ } else {
+ pasid_clear_entry(pte);
+ return -EINVAL;
+ }
+ }
pasid_set_domain_id(pte, did);
pasid_set_address_width(pte, iommu->agaw);
@@ -710,7 +716,8 @@ int intel_pasid_setup_second_level(struct
intel_iommu *iommu,
pasid_set_fault_enable(pte);
pasid_set_page_snoop(pte, !!ecap_smpwc(iommu->ecap));
- if (domain->domain.type == IOMMU_DOMAIN_UNMANAGED)
+ if (ecap_sc_support(iommu->ecap) &&
+ domain->domain.type == IOMMU_DOMAIN_UNMANAGED)
pasid_set_pgsnp(pte);
This should be rebased on top of Jason's enforce coherency series
instead of blindly setting it. No matter whether it's legacy mode
where we set SNP in PTE or scalable mode where we set PGSNP
in PASID entry for entire page table, the trigger point should be
same i.e. when someone calls enforce_cache_coherency().
With Jason's enforce coherency series merged, we even don't need to set
PGSNP bit of a pasid entry for second level translation. 2nd level
always supports SNP in PTEs, so set PGSNP in pasid table entry is
unnecessary.
Any thoughts?
Best regards,
baolu
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