Re: [PATCH v7 3/3] KVM: vmx: handle vm-exit for UMWAIT and TPAUSE
On 7/13/2019 12:03 AM, Sean Christopherson wrote:
On Fri, Jul 12, 2019 at 04:29:07PM +0800, Tao Xu wrote:
--- 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:
Grouped case statements are usually stacked vertically, e.g.:
case EXIT_REASON_UMWAIT:
case EXIT_REASON_TPAUSE:
Ok, thank you for your suggestion.
+ 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");
Blech. I'm guessing this code was copy-pasted from handle_xsaves() and
handle_xrstors(). The blurb of "this should never happen" isn't very
helpful, e.g. the WARN itself makes it pretty obvious that we don't expect
to reach this point. WARN_ONCE would also be preferable, no need to spam
the log in the event things go completely haywire.
Rather than propagate ugly code, what about defining a common helper, e.g.
static int handle_unexpected_vmexit(struct kvm_vcpu *vcpu)
{
kvm_skip_emulated_instruction(vcpu);
WARN_ONCE(1, "Unexpected VM-Exit = 0x%x", vmcs_read32(VM_EXIT_REASON));
return 1;
}
...
{
[EXIT_REASON_XSAVES] = handle_unexpected_vmexit,
[EXIT_REASON_XRSTORS] = handle_unexpected_vmexit,
[EXIT_REASON_UMWAIT] = handle_unexpected_vmexit,
[EXIT_REASON_TPAUSE] = handle_unexpected_vmexit,
}
Thank you Sean, I will do this in next version of patch.
+ 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
Re: [PATCH v7 3/3] KVM: vmx: handle vm-exit for UMWAIT and TPAUSE
On Fri, Jul 12, 2019 at 04:29:07PM +0800, Tao Xu wrote:
> --- 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:
Grouped case statements are usually stacked vertically, e.g.:
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");
Blech. I'm guessing this code was copy-pasted from handle_xsaves() and
handle_xrstors(). The blurb of "this should never happen" isn't very
helpful, e.g. the WARN itself makes it pretty obvious that we don't expect
to reach this point. WARN_ONCE would also be preferable, no need to spam
the log in the event things go completely haywire.
Rather than propagate ugly code, what about defining a common helper, e.g.
static int handle_unexpected_vmexit(struct kvm_vcpu *vcpu)
{
kvm_skip_emulated_instruction(vcpu);
WARN_ONCE(1, "Unexpected VM-Exit = 0x%x", vmcs_read32(VM_EXIT_REASON));
return 1;
}
...
{
[EXIT_REASON_XSAVES] = handle_unexpected_vmexit,
[EXIT_REASON_XRSTORS] = handle_unexpected_vmexit,
[EXIT_REASON_UMWAIT] = handle_unexpected_vmexit,
[EXIT_REASON_TPAUSE] = handle_unexpected_vmexit,
}
> + 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
>
[PATCH v7 3/3] KVM: vmx: handle vm-exit for UMWAIT and TPAUSE
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
Signed-off-by: Jingqi Liu
Signed-off-by: Tao Xu
---
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_FULL62
#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_FAIL1
#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
