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KVM: x86: do mask out upper bits of PAE CR3 

This reverts the change of commit f85c758dbe,
as the behavior it modified was intended.

The VM is running in 32-bit PAE mode, and Table 4-7 of the Intel manual
says:

Table 4-7. Use of CR3 with PAE Paging
Bit Position(s)	Contents
4:0		Ignored
31:5		Physical address of the 32-Byte aligned
		page-directory-pointer table used for linear-address
		translation
63:32		Ignored (these bits exist only on processors supporting
		the Intel-64 architecture)

To placate the static checker, write the mask explicitly as an
unsigned long constant instead of using a 32-bit unsigned constant.

Cc: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: f85c758dbe
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2017-07-24 18:54:38 +02:00
parent fdeaf7e3eb
commit a512177ef3
1 changed files with 2 additions and 2 deletions
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4
arch/x86/kvm/x86.c
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@ -597,8 +597,8 @@ bool pdptrs_changed(struct kvm_vcpu *vcpu)
(unsigned long *)&vcpu->arch.regs_avail)) (unsigned long *)&vcpu->arch.regs_avail))
return true; return true;
gfn = (kvm_read_cr3(vcpu) & ~31ul) >> PAGE_SHIFT; gfn = (kvm_read_cr3(vcpu) & 0xffffffe0ul) >> PAGE_SHIFT;
offset = (kvm_read_cr3(vcpu) & ~31ul) & (PAGE_SIZE - 1); offset = (kvm_read_cr3(vcpu) & 0xffffffe0ul) & (PAGE_SIZE - 1);
r = kvm_read_nested_guest_page(vcpu, gfn, pdpte, offset, sizeof(pdpte), r = kvm_read_nested_guest_page(vcpu, gfn, pdpte, offset, sizeof(pdpte),
PFERR_USER_MASK | PFERR_WRITE_MASK); PFERR_USER_MASK | PFERR_WRITE_MASK);
if (r < 0) if (r < 0)