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Peter Anvin" , Xiao Guangrong Subject: [PATCH 17/15] KVM: X86: Ensure pae_root to be reconstructed for shadow paging if the guest PDPTEs is changed Date: Thu, 11 Nov 2021 22:46:34 +0800 Message-Id: <20211111144634.88972-1-jiangshanlai@gmail.com> X-Mailer: git-send-email 2.19.1.6.gb485710b In-Reply-To: <20211108124407.12187-1-jiangshanlai@gmail.com> References: <20211108124407.12187-1-jiangshanlai@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: Lai Jiangshan For shadow paging, the pae_root needs to be reconstructed before the coming VMENTER if the guest PDPTEs is changed. But not all paths that call load_pdptrs() will cause the pae_root to be reconstructed. Normally, kvm_mmu_reset_context() and kvm_mmu_free_roots() are used to launch later reconstruction. The commit d81135a57aa6("KVM: x86: do not reset mmu if CR0.CD and CR0.NW are changed") skips kvm_mmu_reset_context() after load_pdptrs() when changing CR0.CD and CR0.NW. The commit 21823fbda552("KVM: x86: Invalidate all PGDs for the current PCID on MOV CR3 w/ flush") skips kvm_mmu_free_roots() after load_pdptrs() when rewriting the CR3 with the same value. The commit a91a7c709600("KVM: X86: Don't reset mmu context when toggling X86_CR4_PGE") skips kvm_mmu_reset_context() after load_pdptrs() when changing CR4.PGE. Normally, the guest doesn't change the PDPTEs before doing only the above operation without touching other bits that can force pae_root to be reconstructed. Guests like linux would keep the PDPTEs unchaged for every instance of pagetable. Fixes: d81135a57aa6("KVM: x86: do not reset mmu if CR0.CD and CR0.NW are changed") Fixes: 21823fbda552("KVM: x86: Invalidate all PGDs for the current PCID on MOV CR3 w/ flush") Fixes: a91a7c709600("KVM: X86: Don't reset mmu context when toggling X86_CR4_PGE") Signed-off-by: Lai Jiangshan --- arch/x86/kvm/x86.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 0176eaa86a35..cfba337e46ab 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -832,8 +832,14 @@ int load_pdptrs(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, unsigned long cr3) if (memcmp(mmu->pdptrs, pdpte, sizeof(mmu->pdptrs))) { memcpy(mmu->pdptrs, pdpte, sizeof(mmu->pdptrs)); kvm_register_mark_dirty(vcpu, VCPU_EXREG_PDPTR); - /* Ensure the dirty PDPTEs to be loaded. */ - kvm_make_request(KVM_REQ_LOAD_MMU_PGD, vcpu); + /* + * Ensure the dirty PDPTEs to be loaded for VMX with EPT + * enabled or pae_root to be reconstructed for shadow paging. + */ + if (tdp_enabled) + kvm_make_request(KVM_REQ_LOAD_MMU_PGD, vcpu); + else + kvm_mmu_free_roots(vcpu, vcpu->arch.mmu, KVM_MMU_ROOT_CURRENT); } vcpu->arch.pdptrs_from_userspace = false;