[Xen-devel] [PATCH v2 7/8] x86/vvmx: correctly report vvmcs size

[Sergey Dyasli <sergey.dyasli@xxxxxxxxxx>]

The size of Xen's virtual vmcs region is 4096 bytes (see comment about
Virtual VMCS layout in include/asm-x86/hvm/vmx/vvmx.h). Correctly report
it to the guest in case when VMCS shadowing is not available instead of
providing H/W value (which is usually smaller).

Signed-off-by: Sergey Dyasli <sergey.dyasli@xxxxxxxxxx>
---
v2:
- slight commit message change
---
 xen/arch/x86/hvm/vmx/vvmx.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/xen/arch/x86/hvm/vmx/vvmx.c b/xen/arch/x86/hvm/vmx/vvmx.c
index 2f5370ceed..37d3cdd859 100644
--- a/xen/arch/x86/hvm/vmx/vvmx.c
+++ b/xen/arch/x86/hvm/vmx/vvmx.c
@@ -2101,6 +2101,14 @@ int nvmx_msr_read_intercept(unsigned int msr, u64 
*msr_content)
         data = (host_data & (~0ul << 32)) |
                (vmcs->vmcs_revision_id & 0x7fffffff);
         unmap_domain_page(vmcs);
+
+        if ( !cpu_has_vmx_vmcs_shadowing )
+        {
+            /* Report vmcs_region_size as 4096 */
+            data &= ~VMX_BASIC_VMCS_SIZE_MASK;
+            data |= 1ULL << 44;
+        }
+
         break;
     }
     case MSR_IA32_VMX_PINBASED_CTLS:
-- 
2.17.1


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