[PATCH] KVM: nVMX: support descriptor table exits

[PATCH] KVM: nVMX: support descriptor table exits

[Paolo Bonzini]

These are never used by the host, but they can still be reflected to
the guest.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/include/asm/vmx.h      | 1 +
 arch/x86/include/uapi/asm/vmx.h | 4 ++++
 arch/x86/kvm/vmx.c              | 3 +++
 3 files changed, 8 insertions(+)

diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index a002b07a7099..5ef9848f743f 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -60,6 +60,7 @@
  */
 #define SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES 0x00000001
 #define SECONDARY_EXEC_ENABLE_EPT               0x00000002
+#define SECONDARY_EXEC_DESC			0x00000004
 #define SECONDARY_EXEC_RDTSCP			0x00000008
 #define SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE   0x00000010
 #define SECONDARY_EXEC_ENABLE_VPID              0x00000020
diff --git a/arch/x86/include/uapi/asm/vmx.h b/arch/x86/include/uapi/asm/vmx.h
index 37fee272618f..f9dea4fd4107 100644
--- a/arch/x86/include/uapi/asm/vmx.h
+++ b/arch/x86/include/uapi/asm/vmx.h
@@ -65,6 +65,8 @@
 #define EXIT_REASON_TPR_BELOW_THRESHOLD 43
 #define EXIT_REASON_APIC_ACCESS         44
 #define EXIT_REASON_EOI_INDUCED         45
+#define EXIT_REASON_GDTR_IDTR           46
+#define EXIT_REASON_LDTR_TR             47
 #define EXIT_REASON_EPT_VIOLATION       48
 #define EXIT_REASON_EPT_MISCONFIG       49
 #define EXIT_REASON_INVEPT              50
@@ -113,6 +115,8 @@
 	{ EXIT_REASON_MCE_DURING_VMENTRY,    "MCE_DURING_VMENTRY" }, \
 	{ EXIT_REASON_TPR_BELOW_THRESHOLD,   "TPR_BELOW_THRESHOLD" }, \
 	{ EXIT_REASON_APIC_ACCESS,           "APIC_ACCESS" }, \
+	{ EXIT_REASON_GDTR_IDTR,	     "GDTR_IDTR" }, \
+	{ EXIT_REASON_LDTR_TR,		     "LDTR_TR" }, \
 	{ EXIT_REASON_EPT_VIOLATION,         "EPT_VIOLATION" }, \
 	{ EXIT_REASON_EPT_MISCONFIG,         "EPT_MISCONFIG" }, \
 	{ EXIT_REASON_INVEPT,                "INVEPT" }, \
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 548686d45e13..63302a2b82b6 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2823,6 +2823,7 @@ static void nested_vmx_setup_ctls_msrs(struct vcpu_vmx *vmx)
 	vmx->nested.nested_vmx_secondary_ctls_high &=
 		SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES |
 		SECONDARY_EXEC_RDTSCP |
+		SECONDARY_EXEC_DESC |
 		SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE |
 		SECONDARY_EXEC_ENABLE_VPID |
 		SECONDARY_EXEC_APIC_REGISTER_VIRT |
@@ -7983,6 +7984,8 @@ static bool nested_vmx_exit_handled(struct kvm_vcpu *vcpu)
 		return nested_cpu_has(vmcs12, CPU_BASED_MOV_DR_EXITING);
 	case EXIT_REASON_IO_INSTRUCTION:
 		return nested_vmx_exit_handled_io(vcpu, vmcs12);
+	case EXIT_REASON_GDTR_IDTR: case EXIT_REASON_LDTR_TR:
+		return nested_cpu_has2(vmcs12, SECONDARY_EXEC_DESC);
 	case EXIT_REASON_MSR_READ:
 	case EXIT_REASON_MSR_WRITE:
 		return nested_vmx_exit_handled_msr(vcpu, vmcs12, exit_reason);
-- 
1.8.3.1

Re: [PATCH] KVM: nVMX: support descriptor table exits

[Ladi Prosek]

On Tue, Oct 25, 2016 at 5:05 PM, Paolo Bonzini <pbonzini@redhat.com> wrote:
> These are never used by the host, but they can still be reflected to
> the guest.
>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

This, together with Jan's invvpid patches, fixes the most obvious
Hyper-V on KVM blockers. A nested VM can start, although it gets stuck
in what looks like a page fault loop shortly after reset (still under
investigation).

Tested-by: Ladi Prosek <lprosek@redhat.com>