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From: Lai Jiangshan on 26 May 2010 04:50

In Document/kvm/mmu.txt:
gfn:
Either the guest page table containing the translations shadowed by this
page, or the base page frame for linear translations. See role.direct.

But in __direct_map(), the base gfn calculation is incorrect,
it does not calculate correctly when level=3 or 4.

Reported-by: Marcelo Tosatti <mtosatti(a)redhat.com>
Signed-off-by: Lai Jiangshan <laijs(a)cn.fujitsu.com>
---
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index a5c6719..6986a6f 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1955,7 +1956,10 @@ static int __direct_map(struct kvm_vcpu *vcpu, gpa_t v, int write,
}

if (*iterator.sptep == shadow_trap_nonpresent_pte) {
- pseudo_gfn = (iterator.addr & PT64_DIR_BASE_ADDR_MASK) >> PAGE_SHIFT;
+ u64 base_addr = iterator.addr;
+
+ base_addr &= PT64_LVL_ADDR_MASK(iterator.level);
+ pseudo_gfn = base_addr >> PAGE_SHIFT;
sp = kvm_mmu_get_page(vcpu, pseudo_gfn, iterator.addr,
iterator.level - 1,
1, ACC_ALL, iterator.sptep);




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