[PATCH v6 01/14] X86/nVMX: handle_vmon: Read 4 bytes from guest memory

From: KarimAllah Ahmed
Date: Thu Jan 31 2019 - 15:28:29 EST


Read the data directly from guest memory 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@xxxxxxxxxx>
Signed-off-by: KarimAllah Ahmed <karahmed@xxxxxxxxx>
Reviewed-by: Jim Mattson <jmattson@xxxxxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>

---
v1 -> v2:
- Massage commit message a bit.
---
arch/x86/kvm/vmx/nested.c | 14 +++-----------
1 file changed, 3 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 8ff2052..11b44a9 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -4192,7 +4192,7 @@ 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;
@@ -4241,18 +4241,10 @@ static int handle_vmon(struct kvm_vcpu *vcpu)
if (!PAGE_ALIGNED(vmptr) || (vmptr >> cpuid_maxphyaddr(vcpu)))
return nested_vmx_failInvalid(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)
return nested_vmx_failInvalid(vcpu);

- if (*(u32 *)kmap(page) != VMCS12_REVISION) {
- kunmap(page);
- kvm_release_page_clean(page);
- return nested_vmx_failInvalid(vcpu);
- }
- kunmap(page);
- kvm_release_page_clean(page);
-
vmx->nested.vmxon_ptr = vmptr;
ret = enter_vmx_operation(vcpu);
if (ret)
--
2.7.4