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Subject[PATCH v7 3/3] KVM: vmx: handle vm-exit for UMWAIT and TPAUSE
Date
As the latest Intel 64 and IA-32 Architectures Software Developer's
Manual, UMWAIT and TPAUSE instructions cause a VM exit if the
RDTSC exiting and enable user wait and pause VM-execution
controls are both 1.

This patch is to handle the vm-exit for UMWAIT and TPAUSE as this
should never happen.

Co-developed-by: Jingqi Liu <jingqi.liu@intel.com>
Signed-off-by: Jingqi Liu <jingqi.liu@intel.com>
Signed-off-by: Tao Xu <tao3.xu@intel.com>
---

Changes in v7:
- Add nested exit reason for UMWAIT and TPAUSE (Paolo)
---
arch/x86/include/uapi/asm/vmx.h | 6 +++++-
arch/x86/kvm/vmx/nested.c | 3 +++
arch/x86/kvm/vmx/vmx.c | 16 ++++++++++++++++
3 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/uapi/asm/vmx.h b/arch/x86/include/uapi/asm/vmx.h
index d213ec5c3766..d88d7a68849b 100644
--- a/arch/x86/include/uapi/asm/vmx.h
+++ b/arch/x86/include/uapi/asm/vmx.h
@@ -85,6 +85,8 @@
#define EXIT_REASON_PML_FULL 62
#define EXIT_REASON_XSAVES 63
#define EXIT_REASON_XRSTORS 64
+#define EXIT_REASON_UMWAIT 67
+#define EXIT_REASON_TPAUSE 68

#define VMX_EXIT_REASONS \
{ EXIT_REASON_EXCEPTION_NMI, "EXCEPTION_NMI" }, \
@@ -142,7 +144,9 @@
{ EXIT_REASON_RDSEED, "RDSEED" }, \
{ EXIT_REASON_PML_FULL, "PML_FULL" }, \
{ EXIT_REASON_XSAVES, "XSAVES" }, \
- { EXIT_REASON_XRSTORS, "XRSTORS" }
+ { EXIT_REASON_XRSTORS, "XRSTORS" }, \
+ { EXIT_REASON_UMWAIT, "UMWAIT" }, \
+ { EXIT_REASON_TPAUSE, "TPAUSE" }

#define VMX_ABORT_SAVE_GUEST_MSR_FAIL 1
#define VMX_ABORT_LOAD_HOST_PDPTE_FAIL 2
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index a4d5da34b306..9f91f834ec43 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -5213,6 +5213,9 @@ bool nested_vmx_exit_reflected(struct kvm_vcpu *vcpu, u32 exit_reason)
case EXIT_REASON_ENCLS:
/* SGX is never exposed to L1 */
return false;
+ case EXIT_REASON_UMWAIT: case EXIT_REASON_TPAUSE:
+ return nested_cpu_has2(vmcs12,
+ SECONDARY_EXEC_ENABLE_USR_WAIT_PAUSE);
default:
return true;
}
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 0787f140d155..e026b1313dc3 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -5349,6 +5349,20 @@ static int handle_monitor(struct kvm_vcpu *vcpu)
return handle_nop(vcpu);
}

+static int handle_umwait(struct kvm_vcpu *vcpu)
+{
+ kvm_skip_emulated_instruction(vcpu);
+ WARN(1, "this should never happen\n");
+ return 1;
+}
+
+static int handle_tpause(struct kvm_vcpu *vcpu)
+{
+ kvm_skip_emulated_instruction(vcpu);
+ WARN(1, "this should never happen\n");
+ return 1;
+}
+
static int handle_invpcid(struct kvm_vcpu *vcpu)
{
u32 vmx_instruction_info;
@@ -5559,6 +5573,8 @@ static int (*kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = {
[EXIT_REASON_VMFUNC] = handle_vmx_instruction,
[EXIT_REASON_PREEMPTION_TIMER] = handle_preemption_timer,
[EXIT_REASON_ENCLS] = handle_encls,
+ [EXIT_REASON_UMWAIT] = handle_umwait,
+ [EXIT_REASON_TPAUSE] = handle_tpause,
};

static const int kvm_vmx_max_exit_handlers =
--
2.20.1
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