From: Lai Jiangshan Date: Thu, 16 Dec 2021 02:19:37 +0000 (+0800) Subject: KVM: x86/mmu: Reconstruct shadow page root if the guest PDPTEs is changed X-Git-Tag: v6.6.17~8235^2~140 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=6b123c3a89a90ac6418e4d64b1e23f09d458a77d;p=platform%2Fkernel%2Flinux-rpi.git KVM: x86/mmu: Reconstruct shadow page root if the guest PDPTEs is changed For shadow paging, the page table 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 page tables 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. Guests like linux would keep the PDPTEs unchanged for every instance of pagetable, so this missing reconstruction has no problem for linux guests. 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") Suggested-by: Sean Christopherson Signed-off-by: Lai Jiangshan Message-Id: <20211216021938.11752-3-jiangshanlai@gmail.com> Signed-off-by: Paolo Bonzini --- diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 074a057..9ddad94 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -841,6 +841,13 @@ int load_pdptrs(struct kvm_vcpu *vcpu, unsigned long cr3) } } + /* + * Marking VCPU_EXREG_PDPTR dirty doesn't work for !tdp_enabled. + * Shadow page roots need to be reconstructed instead. + */ + if (!tdp_enabled && memcmp(mmu->pdptrs, pdpte, sizeof(mmu->pdptrs))) + kvm_mmu_free_roots(vcpu, mmu, KVM_MMU_ROOT_CURRENT); + memcpy(mmu->pdptrs, pdpte, sizeof(mmu->pdptrs)); kvm_register_mark_dirty(vcpu, VCPU_EXREG_PDPTR); kvm_make_request(KVM_REQ_LOAD_MMU_PGD, vcpu);