[Xen-devel] [PATCH for-4.11] x86/VT-x: Fix printing of EFER in vmcs_dump_vcpu()

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

This is essentially a "take 2" of c/s 82540b66ce "x86/VT-x: Fix determination
of EFER.LMA in vmcs_dump_vcpu()" because in hindight, that change was more
problematic than useful.

The original reason was to fix the logic for determining when not to print the
PDPTE pointers.  However, mutating the efer variable (particularly LME and
LMA) before printing it interferes with diagnosing vmentry failures.

Instead of modifying efer, change the PDPTE conditional to use
VM_ENTRY_IA32E_MODE.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Jun Nakajima <jun.nakajima@xxxxxxxxx>
CC: Kevin Tian <kevin.tian@xxxxxxxxx>
CC: Juergen Gross <jgross@xxxxxxxx>

This wants taking for 4.11.  It is zero risk for running VMs, but fixes a
regression in the diagnostics of crashed VMs.
---
 xen/arch/x86/hvm/vmx/vmcs.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/xen/arch/x86/hvm/vmx/vmcs.c b/xen/arch/x86/hvm/vmx/vmcs.c
index 70c2fb7..b783ff0 100644
--- a/xen/arch/x86/hvm/vmx/vmcs.c
+++ b/xen/arch/x86/hvm/vmx/vmcs.c
@@ -1788,10 +1788,7 @@ void vmcs_dump_vcpu(struct vcpu *v)
     vmentry_ctl = vmr32(VM_ENTRY_CONTROLS),
     vmexit_ctl = vmr32(VM_EXIT_CONTROLS);
     cr4 = vmr(GUEST_CR4);
-
-    /* EFER.LMA is read as zero, and is loaded from vmentry_ctl on entry. */
-    BUILD_BUG_ON(VM_ENTRY_IA32E_MODE << 1 != EFER_LMA);
-    efer = vmr(GUEST_EFER) | ((vmentry_ctl & VM_ENTRY_IA32E_MODE) << 1);
+    efer = vmr(GUEST_EFER);
 
     printk("*** Guest State ***\n");
     printk("CR0: actual=0x%016lx, shadow=0x%016lx, gh_mask=%016lx\n",
@@ -1801,7 +1798,7 @@ void vmcs_dump_vcpu(struct vcpu *v)
     printk("CR3 = 0x%016lx\n", vmr(GUEST_CR3));
     if ( (v->arch.hvm_vmx.secondary_exec_control &
           SECONDARY_EXEC_ENABLE_EPT) &&
-         (cr4 & X86_CR4_PAE) && !(efer & EFER_LMA) )
+         (cr4 & X86_CR4_PAE) && !(vmentry_ctl & VM_ENTRY_IA32E_MODE) )
     {
         printk("PDPTE0 = 0x%016lx  PDPTE1 = 0x%016lx\n",
                vmr(GUEST_PDPTE(0)), vmr(GUEST_PDPTE(1)));
-- 
2.1.4


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