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KVM: x86/mmu: Allocate PAE root array when using SVM's 32-bit NPT 

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: ee6268ba3a ("KVM: x86: Skip pae_root shadow allocation if tdp enabled")
Cc: stable@vger.kernel.org
Reported-by: Jiri Palecek <jpalecek@web.de>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2019-06-13 10:22:23 -07:00 committed by Paolo Bonzini
parent 6ca00dfafd
commit b6b80c78af
1 changed files with 10 additions and 6 deletions
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16
arch/x86/kvm/mmu.c
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@ -5602,14 +5602,18 @@ 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;
/*
* When emulating 32-bit mode, cr3 is only 32 bits even on x86_64.
* Therefore we need to allocate shadow page tables in the first
* 4GB of memory, which happens to fit the DMA32 zone.
*/
page = alloc_page(GFP_KERNEL_ACCOUNT | __GFP_DMA32);
if (!page)
return -ENOMEM;