linux-kernel - [PATCH 08/15] KVM: x86: Drop current_vcpu in favor of kvm_running

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Message-Id: <20210827005718.585190-9-seanjc@google.com>
Date:   Thu, 26 Aug 2021 17:57:11 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Will Deacon <will@...nel.org>, Mark Rutland <mark.rutland@....com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Marc Zyngier <maz@...nel.org>, Guo Ren <guoren@...nel.org>,
        Nick Hu <nickhu@...estech.com>,
        Greentime Hu <green.hu@...il.com>,
        Vincent Chen <deanbo422@...il.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>, x86@...nel.org,
        Paolo Bonzini <pbonzini@...hat.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>
Cc:     Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        James Morse <james.morse@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        "H. Peter Anvin" <hpa@...or.com>,
        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>,
        Stefano Stabellini <sstabellini@...nel.org>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        linux-csky@...r.kernel.org, linux-riscv@...ts.infradead.org,
        kvm@...r.kernel.org, xen-devel@...ts.xenproject.org,
        Artem Kashkanov <artem.kashkanov@...el.com>,
        Like Xu <like.xu.linux@...il.com>,
        Zhu Lingshan <lingshan.zhu@...el.com>
Subject: [PATCH 08/15] KVM: x86: Drop current_vcpu in favor of kvm_running_vcpu

Now that KVM registers perf callbacks only when the CPU is "in guest",
use kvm_running_vcpu instead of current_vcpu to retrieve the associated
vCPU and drop current_vcpu.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/x86.c | 12 +++++-------
 arch/x86/kvm/x86.h |  4 ----
 2 files changed, 5 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index d4d91944fde7..e337aef60793 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8264,17 +8264,15 @@ static void kvm_timer_init(void)
 			  kvmclock_cpu_online, kvmclock_cpu_down_prep);
 }
 
-DEFINE_PER_CPU(struct kvm_vcpu *, current_vcpu);
-EXPORT_PER_CPU_SYMBOL_GPL(current_vcpu);
-
 static int kvm_is_in_guest(void)
 {
-	return __this_cpu_read(current_vcpu) != NULL;
+	/* x86's callbacks are registered only when handling a guest NMI. */
+	return true;
 }
 
 static int kvm_is_user_mode(void)
 {
-	struct kvm_vcpu *vcpu = __this_cpu_read(current_vcpu);
+	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
 
 	if (WARN_ON_ONCE(!vcpu))
 		return 0;
@@ -8284,7 +8282,7 @@ static int kvm_is_user_mode(void)
 
 static unsigned long kvm_get_guest_ip(void)
 {
-	struct kvm_vcpu *vcpu = __this_cpu_read(current_vcpu);
+	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
 
 	if (WARN_ON_ONCE(!vcpu))
 		return 0;
@@ -8294,7 +8292,7 @@ static unsigned long kvm_get_guest_ip(void)
 
 static void kvm_handle_intel_pt_intr(void)
 {
-	struct kvm_vcpu *vcpu = __this_cpu_read(current_vcpu);
+	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
 
 	if (WARN_ON_ONCE(!vcpu))
 		return;
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index 4c5ba4128b38..f13f15d2fab8 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -393,11 +393,8 @@ static inline void kvm_unregister_perf_callbacks(void)
 	__perf_unregister_guest_info_callbacks();
 }
 
-DECLARE_PER_CPU(struct kvm_vcpu *, current_vcpu);
-
 static inline void kvm_before_interrupt(struct kvm_vcpu *vcpu, bool is_nmi)
 {
-	__this_cpu_write(current_vcpu, vcpu);
 	WRITE_ONCE(vcpu->arch.handling_nmi_from_guest, is_nmi);
 
 	kvm_register_perf_callbacks();
@@ -408,7 +405,6 @@ static inline void kvm_after_interrupt(struct kvm_vcpu *vcpu)
 	kvm_unregister_perf_callbacks();
 
 	WRITE_ONCE(vcpu->arch.handling_nmi_from_guest, false);
-	__this_cpu_write(current_vcpu, NULL);
 }
 
 
-- 
2.33.0.259.gc128427fd7-goog