From 594bef7931089cbdeaf7d8954d54535c8ddd4b30 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Tue, 8 Feb 2022 17:53:55 -0500 Subject: [PATCH] KVM: x86/mmu: do not consult levels when freeing roots Right now, PGD caching requires a complicated dance of first computing the MMU role and passing it to __kvm_mmu_new_pgd(), and then separately calling kvm_init_mmu(). Part of this is due to kvm_mmu_free_roots using mmu->root_level and mmu->shadow_root_level to distinguish whether the page table uses a single root or 4 PAE roots. Because kvm_init_mmu() can overwrite mmu->root_level, kvm_mmu_free_roots() must be called before kvm_init_mmu(). However, even after kvm_init_mmu() there is a way to detect whether the page table may hold PAE roots, as root.hpa isn't backed by a shadow when it points at PAE roots. Using this method results in simpler code, and is one less obstacle in moving all calls to __kvm_mmu_new_pgd() after the MMU has been initialized. Signed-off-by: Paolo Bonzini --- arch/x86/kvm/mmu/mmu.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 5b59333..b97ff76 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -3224,12 +3224,15 @@ void kvm_mmu_free_roots(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, struct kvm *kvm = vcpu->kvm; int i; LIST_HEAD(invalid_list); - bool free_active_root = roots_to_free & KVM_MMU_ROOT_CURRENT; + bool free_active_root; BUILD_BUG_ON(KVM_MMU_NUM_PREV_ROOTS >= BITS_PER_LONG); /* Before acquiring the MMU lock, see if we need to do any real work. */ - if (!(free_active_root && VALID_PAGE(mmu->root.hpa))) { + free_active_root = (roots_to_free & KVM_MMU_ROOT_CURRENT) + && VALID_PAGE(mmu->root.hpa); + + if (!free_active_root) { for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) if ((roots_to_free & KVM_MMU_ROOT_PREVIOUS(i)) && VALID_PAGE(mmu->prev_roots[i].hpa)) @@ -3247,8 +3250,7 @@ void kvm_mmu_free_roots(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, &invalid_list); if (free_active_root) { - if (mmu->shadow_root_level >= PT64_ROOT_4LEVEL && - (mmu->root_level >= PT64_ROOT_4LEVEL || mmu->direct_map)) { + if (to_shadow_page(mmu->root.hpa)) { mmu_free_root_page(kvm, &mmu->root.hpa, &invalid_list); } else if (mmu->pae_root) { for (i = 0; i < 4; ++i) { -- 2.7.4