[PATCH 6.6.y 0/2] KVM pgtable fixes

[PATCH 6.6.y 0/2] KVM pgtable fixes

[Will Deacon]

Hi stable folks,

I noticed that these two KVM/arm64 pgtable fixes are missing from 6.6.y
so I've done the backports. The second one is also needed in 6.1.y but
it needs some tweaks so I'll post a separate backport for that.

Cheers,

Will

Cc: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oliver.upton@linux.dev>
cc: kvmarm@lists.linux.dev

--->8

Will Deacon (2):
  KVM: arm64: Don't defer TLB invalidation when zapping table entries
  KVM: arm64: Don't pass a TLBI level hint when zapping table entries

 arch/arm64/kvm/hyp/pgtable.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

-- 
2.46.0.184.g6999bdac58-goog

[PATCH 6.6.y 1/2] KVM: arm64: Don't defer TLB invalidation when zapping table entries

[Will Deacon]

commit f62d4c3eb687d87b616b4279acec7862553bda77 upstream.

Commit 7657ea920c54 ("KVM: arm64: Use TLBI range-based instructions for
unmap") introduced deferred TLB invalidation for the stage-2 page-table
so that range-based invalidation can be used for the accumulated
addresses. This works fine if the structure of the page-tables remains
unchanged, but if entire tables are zapped and subsequently freed then
we transiently leave the hardware page-table walker with a reference
to freed memory thanks to the translation walk caches. For example,
stage2_unmap_walker() will free page-table pages:

	if (childp)
		mm_ops->put_page(childp);

and issue the TLB invalidation later in kvm_pgtable_stage2_unmap():

	if (stage2_unmap_defer_tlb_flush(pgt))
		/* Perform the deferred TLB invalidations */
		kvm_tlb_flush_vmid_range(pgt->mmu, addr, size);

For now, take the conservative approach and invalidate the TLB eagerly
when we clear a table entry. Note, however, that the existing level
hint passed to __kvm_tlb_flush_vmid_ipa() is incorrect and will be
fixed in a subsequent patch.

Cc: Raghavendra Rao Ananta <rananta@google.com>
Cc: Shaoqin Huang <shahuang@redhat.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oliver.upton@linux.dev>
Reviewed-by: Shaoqin Huang <shahuang@redhat.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20240327124853.11206-2-will@kernel.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Cc: <stable@vger.kernel.org> # 6.6.y only
Signed-off-by: Will Deacon <will@kernel.org>
---
 arch/arm64/kvm/hyp/pgtable.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index 15aa9bad1c28..6692327fabe7 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -861,9 +861,11 @@ static void stage2_unmap_put_pte(const struct kvm_pgtable_visit_ctx *ctx,
 	if (kvm_pte_valid(ctx->old)) {
 		kvm_clear_pte(ctx->ptep);
 
-		if (!stage2_unmap_defer_tlb_flush(pgt))
+		if (!stage2_unmap_defer_tlb_flush(pgt) ||
+		    kvm_pte_table(ctx->old, ctx->level)) {
 			kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, mmu,
 					ctx->addr, ctx->level);
+		}
 	}
 
 	mm_ops->put_page(ctx->ptep);
-- 
2.46.0.184.g6999bdac58-goog

[PATCH 6.6.y 2/2] KVM: arm64: Don't pass a TLBI level hint when zapping table entries

[Will Deacon]

commit 36e008323926036650299cfbb2dca704c7aba849 upstream.

The TLBI level hints are for leaf entries only, so take care not to pass
them incorrectly after clearing a table entry.

Cc: Gavin Shan <gshan@redhat.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Quentin Perret <qperret@google.com>
Fixes: 82bb02445de5 ("KVM: arm64: Implement kvm_pgtable_hyp_unmap() at EL2")
Fixes: 6d9d2115c480 ("KVM: arm64: Add support for stage-2 map()/unmap() in generic page-table")
Signed-off-by: Will Deacon <will@kernel.org>
Reviewed-by: Shaoqin Huang <shahuang@redhat.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20240327124853.11206-3-will@kernel.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Cc: <stable@vger.kernel.org> # 6.6.y only
[will@: Use '0' instead of TLBI_TTL_UNKNOWN to indicate "no level"]
Signed-off-by: Will Deacon <will@kernel.org>
---
 arch/arm64/kvm/hyp/pgtable.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index 6692327fabe7..ca0bf0b92ca0 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -523,7 +523,7 @@ static int hyp_unmap_walker(const struct kvm_pgtable_visit_ctx *ctx,
 
 		kvm_clear_pte(ctx->ptep);
 		dsb(ishst);
-		__tlbi_level(vae2is, __TLBI_VADDR(ctx->addr, 0), ctx->level);
+		__tlbi_level(vae2is, __TLBI_VADDR(ctx->addr, 0), 0);
 	} else {
 		if (ctx->end - ctx->addr < granule)
 			return -EINVAL;
@@ -861,10 +861,12 @@ static void stage2_unmap_put_pte(const struct kvm_pgtable_visit_ctx *ctx,
 	if (kvm_pte_valid(ctx->old)) {
 		kvm_clear_pte(ctx->ptep);
 
-		if (!stage2_unmap_defer_tlb_flush(pgt) ||
-		    kvm_pte_table(ctx->old, ctx->level)) {
-			kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, mmu,
-					ctx->addr, ctx->level);
+		if (kvm_pte_table(ctx->old, ctx->level)) {
+			kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, mmu, ctx->addr,
+				     0);
+		} else if (!stage2_unmap_defer_tlb_flush(pgt)) {
+			kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, mmu, ctx->addr,
+				     ctx->level);
 		}
 	}
 
-- 
2.46.0.184.g6999bdac58-goog

Re: [PATCH 6.6.y 0/2] KVM pgtable fixes

[Greg KH]

On Thu, Aug 15, 2024 at 01:46:24PM +0100, Will Deacon wrote:
> Hi stable folks,
> 
> I noticed that these two KVM/arm64 pgtable fixes are missing from 6.6.y
> so I've done the backports. The second one is also needed in 6.1.y but
> it needs some tweaks so I'll post a separate backport for that.

Now queued up, thanks.

greg k-h