From bbddf4bf1f91227c11e9e95438f5fbab3b1e7f26 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Thu, 4 Jul 2019 11:39:43 +0800 Subject: [PATCH] KVM: x86/mmu: Allocate PAE root array when using SVM's 32-bit NPT commit b6b80c78af838bef17501416d5d383fedab0010a upstream. SVM's Nested Page Tables (NPT) reuses x86 paging for the host-controlled page walk. For 32-bit KVM, this means PAE paging is used even when TDP is enabled, i.e. the PAE root array needs to be allocated. Fixes: ee6268ba3a68 ("KVM: x86: Skip pae_root shadow allocation if tdp enabled") Cc: stable@vger.kernel.org Reported-by: Jiri Palecek Signed-off-by: Sean Christopherson Signed-off-by: Paolo Bonzini Cc: Jiri Palecek Signed-off-by: Greg Kroah-Hartman Signed-off-by: Yang Yingliang --- arch/x86/kvm/mmu.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 779ed52047d1..e0f982e35c96 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -5386,7 +5386,16 @@ static int alloc_mmu_pages(struct kvm_vcpu *vcpu) struct page *page; int i; - if (tdp_enabled) + /* + * When using PAE paging, the four PDPTEs are treated as 'root' pages, + * while the PDP table is a per-vCPU construct that's allocated at MMU + * creation. When emulating 32-bit mode, cr3 is only 32 bits even on + * x86_64. Therefore we need to allocate the PDP table in the first + * 4GB of memory, which happens to fit the DMA32 zone. Except for + * SVM's 32-bit NPT support, TDP paging doesn't use PAE paging and can + * skip allocating the PDP table. + */ + if (tdp_enabled && kvm_x86_ops->get_tdp_level(vcpu) > PT32E_ROOT_LEVEL) return 0; /* -- GitLab