linux-kernel - [PATCH 5.16 08/28] KVM: x86: Register Processor Trace interrupt hook iff PT enabled in guest

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Date:   Tue, 18 Jan 2022 17:06:03 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Artem Kashkanov <artem.kashkanov@...el.com>,
        Sean Christopherson <seanjc@...gle.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Paolo Bonzini <pbonzini@...hat.com>
Subject: [PATCH 5.16 08/28] KVM: x86: Register Processor Trace interrupt hook iff PT enabled in guest

From: Sean Christopherson <seanjc@...gle.com>

commit f4b027c5c8199abd4fb6f00d67d380548dbfdfa8 upstream.

Override the Processor Trace (PT) interrupt handler for guest mode if and
only if PT is configured for host+guest mode, i.e. is being used
independently by both host and guest.  If PT is configured for system
mode, the host fully controls PT and must handle all events.

Fixes: 8479e04e7d6b ("KVM: x86: Inject PMI for KVM guest")
Reported-by: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Reported-by: Artem Kashkanov <artem.kashkanov@...el.com>
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Acked-by: Paolo Bonzini <pbonzini@...hat.com>
Cc: stable@...r.kernel.org
Link: https://lore.kernel.org/r/20211111020738.2512932-4-seanjc@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/x86/include/asm/kvm_host.h |    1 +
 arch/x86/kvm/vmx/vmx.c          |    1 +
 arch/x86/kvm/x86.c              |    5 ++++-
 3 files changed, 6 insertions(+), 1 deletion(-)

--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1519,6 +1519,7 @@ struct kvm_x86_init_ops {
 	int (*disabled_by_bios)(void);
 	int (*check_processor_compatibility)(void);
 	int (*hardware_setup)(void);
+	bool (*intel_pt_intr_in_guest)(void);
 
 	struct kvm_x86_ops *runtime_ops;
 };
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7905,6 +7905,7 @@ static struct kvm_x86_init_ops vmx_init_
 	.disabled_by_bios = vmx_disabled_by_bios,
 	.check_processor_compatibility = vmx_check_processor_compat,
 	.hardware_setup = hardware_setup,
+	.intel_pt_intr_in_guest = vmx_pt_mode_is_host_guest,
 
 	.runtime_ops = &vmx_x86_ops,
 };
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8560,7 +8560,7 @@ static struct perf_guest_info_callbacks
 	.is_in_guest		= kvm_is_in_guest,
 	.is_user_mode		= kvm_is_user_mode,
 	.get_guest_ip		= kvm_get_guest_ip,
-	.handle_intel_pt_intr	= kvm_handle_intel_pt_intr,
+	.handle_intel_pt_intr	= NULL,
 };
 
 #ifdef CONFIG_X86_64
@@ -11266,6 +11266,8 @@ int kvm_arch_hardware_setup(void *opaque
 	memcpy(&kvm_x86_ops, ops->runtime_ops, sizeof(kvm_x86_ops));
 	kvm_ops_static_call_update();
 
+	if (ops->intel_pt_intr_in_guest && ops->intel_pt_intr_in_guest())
+		kvm_guest_cbs.handle_intel_pt_intr = kvm_handle_intel_pt_intr;
 	perf_register_guest_info_callbacks(&kvm_guest_cbs);
 
 	if (!kvm_cpu_cap_has(X86_FEATURE_XSAVES))
@@ -11296,6 +11298,7 @@ int kvm_arch_hardware_setup(void *opaque
 void kvm_arch_hardware_unsetup(void)
 {
 	perf_unregister_guest_info_callbacks(&kvm_guest_cbs);
+	kvm_guest_cbs.handle_intel_pt_intr = NULL;
 
 	static_call(kvm_x86_hardware_unsetup)();
 }