linux-kernel - [PATCH 2/3] KVM: x86: Register Processor Trace interrupt hook iff PT enabled in guest

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Message-Id: <20210823193709.55886-3-seanjc@google.com>
Date:   Mon, 23 Aug 2021 12:37:08 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, Artem Kashkanov <artem.kashkanov@...el.com>
Subject: [PATCH 2/3] KVM: x86: Register Processor Trace interrupt hook iff PT
 enabled in guest

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")
Cc: stable@...r.kernel.org
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>
---
 arch/x86/include/asm/kvm_host.h | 1 +
 arch/x86/kvm/pmu.h              | 1 +
 arch/x86/kvm/vmx/vmx.c          | 1 +
 arch/x86/kvm/x86.c              | 4 +++-
 4 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 09b256db394a..1ea4943a73d7 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1494,6 +1494,7 @@ 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;
 };
diff --git a/arch/x86/kvm/pmu.h b/arch/x86/kvm/pmu.h
index 0e4f2b1fa9fb..b06dbbd7eeeb 100644
--- a/arch/x86/kvm/pmu.h
+++ b/arch/x86/kvm/pmu.h
@@ -41,6 +41,7 @@ struct kvm_pmu_ops {
 	void (*reset)(struct kvm_vcpu *vcpu);
 	void (*deliver_pmi)(struct kvm_vcpu *vcpu);
 	void (*cleanup)(struct kvm_vcpu *vcpu);
+	void (*handle_intel_pt_intr)(void);
 };
 
 static inline u64 pmc_bitmask(struct kvm_pmc *pmc)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index fada1055f325..f19d72136f77 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7896,6 +7896,7 @@ static struct kvm_x86_init_ops vmx_init_ops __initdata = {
 	.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,
 };
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index fb6015f97f9e..b5ade47dad9c 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8305,7 +8305,7 @@ static struct perf_guest_info_callbacks kvm_guest_cbs = {
 	.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
@@ -11061,6 +11061,8 @@ 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))
-- 
2.33.0.rc2.250.ged5fa647cd-goog