Commit 01a02a98 authored Jun 13, 2019 by Sean Christopherson Committed by Greg Kroah-Hartman Jul 03, 2019

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: ee6268ba ("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>
Cc: Jiri Palecek <jpalecek@web.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 32746032

arch/x86/kvm/mmu.c

+10 −1

Original line number	Diff line number	Diff line
		@@ -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;

		/*