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From: Sean Christopherson <seanjc@google.com>
To: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Sean Christopherson <seanjc@google.com>,
	Paolo Bonzini <pbonzini@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@kernel.org>, Namhyung Kim <namhyung@kernel.org>,
	linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
	kvm@vger.kernel.org, Like Xu <like.xu.linux@gmail.com>
Subject: [PATCH v2 7/7] KVM: VMX: Simplify capability check when handling PERF_CAPABILITIES write
Date: Wed,  3 Aug 2022 19:26:58 +0000	[thread overview]
Message-ID: <20220803192658.860033-8-seanjc@google.com> (raw)
In-Reply-To: <20220803192658.860033-1-seanjc@google.com>

Explicitly check for the absence of host support for LBRs or PEBS when
userspace attempts to enable said features by writing PERF_CAPABILITIES.
Comparing host support against the incoming value is unnecessary and
weird since the checks are buried inside an if-statement that verifies
userspace wants to enable the feature.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/vmx/vmx.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index d7f8331d6f7e..0ada0ee234b7 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2323,15 +2323,13 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 		if (data && !vcpu_to_pmu(vcpu)->version)
 			return 1;
 		if (data & PMU_CAP_LBR_FMT) {
-			if ((data & PMU_CAP_LBR_FMT) !=
-			    (vmx_get_perf_capabilities() & PMU_CAP_LBR_FMT))
+			if (!(vmx_get_perf_capabilities() & PMU_CAP_LBR_FMT))
 				return 1;
 			if (!cpuid_model_is_consistent(vcpu))
 				return 1;
 		}
 		if (data & PERF_CAP_PEBS_FORMAT) {
-			if ((data & PERF_CAP_PEBS_MASK) !=
-			    (vmx_get_perf_capabilities() & PERF_CAP_PEBS_MASK))
+			if (!(vmx_get_perf_capabilities() & PERF_CAP_PEBS_MASK))
 				return 1;
 			if (!guest_cpuid_has(vcpu, X86_FEATURE_DS))
 				return 1;
-- 
2.37.1.559.g78731f0fdb-goog


  parent reply	other threads:[~2022-08-03 19:27 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-08-03 19:26 [PATCH v2 0/7] KVM: x86: Intel PERF_CAPABILITIES fixes and cleanups Sean Christopherson
2022-08-03 19:26 ` [PATCH v2 1/7] KVM: x86: Refresh PMU after writes to MSR_IA32_PERF_CAPABILITIES Sean Christopherson
2022-08-03 19:26 ` [PATCH v2 2/7] perf/x86/core: Remove unnecessary stubs provided for KVM-only helpers Sean Christopherson
2022-08-04  8:49   ` Like Xu
2022-08-04 15:07     ` Sean Christopherson
2022-08-03 19:26 ` [PATCH v2 3/7] perf/x86/core: Drop the unnecessary return value from x86_perf_get_lbr() Sean Christopherson
2022-08-03 19:26 ` [PATCH v2 4/7] KVM: VMX: Advertise PMU LBRs if and only if perf supports LBRs Sean Christopherson
2022-08-03 19:26 ` [PATCH v2 5/7] KVM: VMX: Use proper type-safe functions for vCPU => LBRs helpers Sean Christopherson
2022-08-03 19:26 ` [PATCH v2 6/7] KVM: VMX: Adjust number of LBR records for PERF_CAPABILITIES at refresh Sean Christopherson
2022-08-03 19:26 ` Sean Christopherson [this message]
2022-08-04  7:52   ` [PATCH v2 7/7] KVM: VMX: Simplify capability check when handling PERF_CAPABILITIES write Like Xu
2022-08-04 15:00     ` Sean Christopherson

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