From: Will Deacon <will@kernel.org> To: kvmarm@lists.linux.dev Cc: linux-arm-kernel@lists.infradead.org, Will Deacon <will@kernel.org>, Catalin Marinas <catalin.marinas@arm.com>, Gavin Shan <gshan@redhat.com>, Marc Zyngier <maz@kernel.org>, Mostafa Saleh <smostafa@google.com>, Oliver Upton <oliver.upton@linux.dev>, Quentin Perret <qperret@google.com>, Raghavendra Rao Ananta <rananta@google.com>, Ryan Roberts <ryan.roberts@arm.com>, Shaoqin Huang <shahuang@redhat.com>, Suzuki K Poulose <suzuki.poulose@arm.com>, Zenghui Yu <yuzenghui@huawei.com> Subject: [PATCH 1/3] KVM: arm64: Don't defer TLB invalidation when zapping table entries Date: Mon, 25 Mar 2024 18:51:56 +0000 [thread overview] Message-ID: <20240325185158.8565-2-will@kernel.org> (raw) In-Reply-To: <20240325185158.8565-1-will@kernel.org> 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. 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> 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 3fae5830f8d2..de0b667ba296 100644 --- a/arch/arm64/kvm/hyp/pgtable.c +++ b/arch/arm64/kvm/hyp/pgtable.c @@ -896,9 +896,11 @@ 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); -- 2.44.0.396.g6e790dbe36-goog
WARNING: multiple messages have this Message-ID (diff)
From: Will Deacon <will@kernel.org> To: kvmarm@lists.linux.dev Cc: linux-arm-kernel@lists.infradead.org, Will Deacon <will@kernel.org>, Catalin Marinas <catalin.marinas@arm.com>, Gavin Shan <gshan@redhat.com>, Marc Zyngier <maz@kernel.org>, Mostafa Saleh <smostafa@google.com>, Oliver Upton <oliver.upton@linux.dev>, Quentin Perret <qperret@google.com>, Raghavendra Rao Ananta <rananta@google.com>, Ryan Roberts <ryan.roberts@arm.com>, Shaoqin Huang <shahuang@redhat.com>, Suzuki K Poulose <suzuki.poulose@arm.com>, Zenghui Yu <yuzenghui@huawei.com> Subject: [PATCH 1/3] KVM: arm64: Don't defer TLB invalidation when zapping table entries Date: Mon, 25 Mar 2024 18:51:56 +0000 [thread overview] Message-ID: <20240325185158.8565-2-will@kernel.org> (raw) In-Reply-To: <20240325185158.8565-1-will@kernel.org> 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. 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> 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 3fae5830f8d2..de0b667ba296 100644 --- a/arch/arm64/kvm/hyp/pgtable.c +++ b/arch/arm64/kvm/hyp/pgtable.c @@ -896,9 +896,11 @@ 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); -- 2.44.0.396.g6e790dbe36-goog _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2024-03-25 18:52 UTC|newest] Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top 2024-03-25 18:51 [PATCH 0/3] KVM: arm64: TLBI fixes for the pgtable code Will Deacon 2024-03-25 18:51 ` Will Deacon 2024-03-25 18:51 ` Will Deacon [this message] 2024-03-25 18:51 ` [PATCH 1/3] KVM: arm64: Don't defer TLB invalidation when zapping table entries Will Deacon 2024-03-26 8:34 ` Oliver Upton 2024-03-26 8:34 ` Oliver Upton 2024-03-26 14:31 ` Oliver Upton 2024-03-26 14:31 ` Oliver Upton 2024-03-26 16:10 ` Will Deacon 2024-03-26 16:10 ` Will Deacon 2024-03-26 16:14 ` Oliver Upton 2024-03-26 16:14 ` Oliver Upton 2024-03-25 18:51 ` [PATCH 2/3] KVM: arm64: Don't pass a TLBI level hint " Will Deacon 2024-03-25 18:51 ` Will Deacon 2024-03-26 8:37 ` Oliver Upton 2024-03-26 8:37 ` Oliver Upton 2024-03-26 9:34 ` Will Deacon 2024-03-26 9:34 ` Will Deacon 2024-03-26 13:12 ` Oliver Upton 2024-03-26 13:12 ` Oliver Upton 2024-03-25 18:51 ` [PATCH 3/3] KVM: arm64: Use TLBI_TTL_UNKNOWN in __kvm_tlb_flush_vmid_range() Will Deacon 2024-03-25 18:51 ` Will Deacon 2024-03-26 13:48 ` Ryan Roberts 2024-03-26 13:48 ` Ryan Roberts 2024-03-27 12:45 ` Will Deacon 2024-03-27 12:45 ` Will Deacon
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