[PATCH v4 4/5] KVM: x86: let reexecute_instruction work for tdp

Xiao Guangrong
2013-01-04T13:56:16Z

Currently, reexecute_instruction refused to retry all instructions. If
nested npt is used, the emulation may be caused by shadow page, it can
be fixed by dropping the shadow page

Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
---
arch/x86/kvm/x86.c | 28 ++++++++++++++++++++++------
1 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ad39018..b0a3678 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4753,17 +4753,33 @@ static int handle_emulation_failure(struct kvm_vcpu *vcpu)
return r;
}

-static bool reexecute_instruction(struct kvm_vcpu *vcpu, gva_t gva)
+static bool reexecute_instruction(struct kvm_vcpu *vcpu, unsigned long cr2)
{
- gpa_t gpa;
+ gpa_t gpa = cr2;
pfn_t pfn;
+ unsigned int indirect_shadow_pages;
+
+ spin_lock(&vcpu->kvm->mmu_lock);
+ indirect_shadow_pages = vcpu->kvm->arch.indirect_shadow_pages;
+ spin_unlock(&vcpu->kvm->mmu_lock);

- if (tdp_enabled)
+ if (!indirect_shadow_pages)
return false;

- gpa = kvm_mmu_gva_to_gpa_read(vcpu, gva, NULL);
- if (gpa == UNMAPPED_GVA)
- return true; /* let cpu generate fault */
+ if (!vcpu->arch.mmu.direct_map) {
+ /*
+ * Write permission should be allowed since only
+ * write access need to be emulated.
+ */
+ gpa = kvm_mmu_gva_to_gpa_write(vcpu, cr2, NULL);
+
+ /*
+ * If the mapping is invalid in guest, let cpu retry
+ * it to generate fault.
+ */
+ if (gpa == UNMAPPED_GVA)
+ return true;
+ }

/*
* if emulation was due to access to shadowed page table
--
1.7.7.6