[PATCH v2 01/12] X86/nVMX: handle_vmon: Read 4 bytes from guest memory

KarimAllah Ahmed
2018-04-15T21:55:49Z

Read the data directly from guest memory instead instead of the
map->read->unmap sequence. This also avoids using kvm_vcpu_gpa_to_page()
and kmap() which assumes that there is a "struct page" for guest memory.

Suggested-by: Jim Mattson <jmattson@google.com>
Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
---
v1 -> v2:
- Massage commit message a bit.
---
arch/x86/kvm/vmx.c | 14 +++-----------
1 file changed, 3 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 55ab0ca..77fc1ee 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -7672,7 +7672,7 @@ static int handle_vmon(struct kvm_vcpu *vcpu)
{
int ret;
gpa_t vmptr;
- struct page *page;
+ uint32_t revision;
struct vcpu_vmx *vmx = to_vmx(vcpu);
const u64 VMXON_NEEDED_FEATURES = FEATURE_CONTROL_LOCKED
| FEATURE_CONTROL_VMXON_ENABLED_OUTSIDE_SMX;
@@ -7718,19 +7718,11 @@ static int handle_vmon(struct kvm_vcpu *vcpu)
return kvm_skip_emulated_instruction(vcpu);
}

- page = kvm_vcpu_gpa_to_page(vcpu, vmptr);
- if (is_error_page(page)) {
+ if (kvm_read_guest(vcpu->kvm, vmptr, &revision, sizeof(revision)) ||
+ revision != VMCS12_REVISION) {
nested_vmx_failInvalid(vcpu);
return kvm_skip_emulated_instruction(vcpu);
}
- if (*(u32 *)kmap(page) != VMCS12_REVISION) {
- kunmap(page);
- kvm_release_page_clean(page);
- nested_vmx_failInvalid(vcpu);
- return kvm_skip_emulated_instruction(vcpu);
- }
- kunmap(page);
- kvm_release_page_clean(page);

vmx->nested.vmxon_ptr = vmptr;
ret = enter_vmx_operation(vcpu);
--
2.7.4