From: Punit Agrawal <punit.agrawal@arm.com> To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Cc: Punit Agrawal <punit.agrawal@arm.com>, Christoffer Dall <christoffer.dall@linaro.org>, Marc Zyngier <marc.zyngier@arm.com>, Steven Rostedt <rostedt@goodmis.org>, Ingo Molnar <mingo@redhat.com>, Will Deacon <will.deacon@arm.com> Subject: [RFC PATCH 7/7] arm64: KVM: Enable selective trapping of TLB instructions Date: Tue, 16 Aug 2016 11:45:12 +0100 [thread overview] Message-ID: <1471344312-26685-8-git-send-email-punit.agrawal@arm.com> (raw) In-Reply-To: <1471344312-26685-1-git-send-email-punit.agrawal@arm.com> The TTLB bit of Hypervisor Control Register (HCR_EL2) controls the trapping of guest TLB maintenance instructions. Taking the trap requires a switch to the hypervisor and is an expensive operation. Enable selective trapping of guest TLB instructions when the associated perf trace event is enabled for a specific virtual machine. Signed-off-by: Punit Agrawal <punit.agrawal@arm.com> Cc: Christoffer Dall <christoffer.dall@linaro.org> Cc: Marc Zyngier <marc.zyngier@arm.com> --- arch/arm64/kvm/perf_trace.c | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) diff --git a/arch/arm64/kvm/perf_trace.c b/arch/arm64/kvm/perf_trace.c index 8bacd18..f26da1d 100644 --- a/arch/arm64/kvm/perf_trace.c +++ b/arch/arm64/kvm/perf_trace.c @@ -17,6 +17,8 @@ #include <linux/kvm_host.h> #include <linux/trace_events.h> +#include <asm/kvm_emulate.h> + typedef int (*perf_trace_callback_fn)(struct kvm *kvm, bool enable); struct kvm_trace_hook { @@ -24,7 +26,37 @@ struct kvm_trace_hook { perf_trace_callback_fn setup_fn; }; +static int tlb_invalidate_trap(struct kvm *kvm, bool enable) +{ + int i; + struct kvm_vcpu *vcpu; + + /* + * Halt the VM to ensure atomic update across all vcpus (this + * avoids racy behaviour against other modifications of + * HCR_EL2 such as kvm_toggle_cache/kvm_set_way_flush). + */ + kvm_arm_halt_guest(kvm); + kvm_for_each_vcpu(i, vcpu, kvm) { + unsigned long hcr = vcpu_get_hcr(vcpu); + + if (enable) + hcr |= HCR_TTLB; + else + hcr &= ~HCR_TTLB; + + vcpu_set_hcr(vcpu, hcr); + } + kvm_arm_resume_guest(kvm); + + return 0; +} + static struct kvm_trace_hook trace_hook[] = { + { + .key = "kvm_tlb_invalidate", + .setup_fn = tlb_invalidate_trap, + }, { }, }; -- 2.8.1
WARNING: multiple messages have this Message-ID (diff)
From: punit.agrawal@arm.com (Punit Agrawal) To: linux-arm-kernel@lists.infradead.org Subject: [RFC PATCH 7/7] arm64: KVM: Enable selective trapping of TLB instructions Date: Tue, 16 Aug 2016 11:45:12 +0100 [thread overview] Message-ID: <1471344312-26685-8-git-send-email-punit.agrawal@arm.com> (raw) In-Reply-To: <1471344312-26685-1-git-send-email-punit.agrawal@arm.com> The TTLB bit of Hypervisor Control Register (HCR_EL2) controls the trapping of guest TLB maintenance instructions. Taking the trap requires a switch to the hypervisor and is an expensive operation. Enable selective trapping of guest TLB instructions when the associated perf trace event is enabled for a specific virtual machine. Signed-off-by: Punit Agrawal <punit.agrawal@arm.com> Cc: Christoffer Dall <christoffer.dall@linaro.org> Cc: Marc Zyngier <marc.zyngier@arm.com> --- arch/arm64/kvm/perf_trace.c | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) diff --git a/arch/arm64/kvm/perf_trace.c b/arch/arm64/kvm/perf_trace.c index 8bacd18..f26da1d 100644 --- a/arch/arm64/kvm/perf_trace.c +++ b/arch/arm64/kvm/perf_trace.c @@ -17,6 +17,8 @@ #include <linux/kvm_host.h> #include <linux/trace_events.h> +#include <asm/kvm_emulate.h> + typedef int (*perf_trace_callback_fn)(struct kvm *kvm, bool enable); struct kvm_trace_hook { @@ -24,7 +26,37 @@ struct kvm_trace_hook { perf_trace_callback_fn setup_fn; }; +static int tlb_invalidate_trap(struct kvm *kvm, bool enable) +{ + int i; + struct kvm_vcpu *vcpu; + + /* + * Halt the VM to ensure atomic update across all vcpus (this + * avoids racy behaviour against other modifications of + * HCR_EL2 such as kvm_toggle_cache/kvm_set_way_flush). + */ + kvm_arm_halt_guest(kvm); + kvm_for_each_vcpu(i, vcpu, kvm) { + unsigned long hcr = vcpu_get_hcr(vcpu); + + if (enable) + hcr |= HCR_TTLB; + else + hcr &= ~HCR_TTLB; + + vcpu_set_hcr(vcpu, hcr); + } + kvm_arm_resume_guest(kvm); + + return 0; +} + static struct kvm_trace_hook trace_hook[] = { + { + .key = "kvm_tlb_invalidate", + .setup_fn = tlb_invalidate_trap, + }, { }, }; -- 2.8.1
next prev parent reply other threads:[~2016-08-16 10:47 UTC|newest] Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-08-16 10:45 [RFC PATCH 0/7] Add support for monitoring guest TLB operations Punit Agrawal 2016-08-16 10:45 ` Punit Agrawal 2016-08-16 10:45 ` [RFC PATCH 1/7] perf/trace: Add notification for perf trace events Punit Agrawal 2016-08-16 10:45 ` Punit Agrawal 2016-08-31 11:01 ` Punit Agrawal 2016-08-31 11:01 ` Punit Agrawal 2016-08-31 11:01 ` Punit Agrawal 2016-08-16 10:45 ` [RFC PATCH 2/7] KVM: Track the pid of the VM process Punit Agrawal 2016-08-16 10:45 ` Punit Agrawal 2016-08-16 10:45 ` [RFC PATCH 3/7] KVM: arm/arm64: Register perf trace event notifier Punit Agrawal 2016-08-16 10:45 ` Punit Agrawal 2016-08-16 10:45 ` [RFC PATCH 4/7] arm64: tlbflush.h: add __tlbi() macro Punit Agrawal 2016-08-16 10:45 ` Punit Agrawal 2016-08-19 13:24 ` Will Deacon 2016-08-19 13:24 ` Will Deacon 2016-08-19 13:24 ` Will Deacon 2016-08-19 13:34 ` Punit Agrawal 2016-08-19 13:34 ` Punit Agrawal 2016-08-16 10:45 ` [RFC PATCH 5/7] arm64/kvm: hyp: tlb: use __tlbi() helper Punit Agrawal 2016-08-16 10:45 ` Punit Agrawal 2016-08-16 10:45 ` [RFC PATCH 6/7] arm64: KVM: Handle trappable TLB instructions Punit Agrawal 2016-08-16 10:45 ` Punit Agrawal 2016-08-19 15:18 ` Will Deacon 2016-08-19 15:18 ` Will Deacon 2016-08-24 10:40 ` Punit Agrawal 2016-08-24 10:40 ` Punit Agrawal 2016-08-26 9:37 ` Punit Agrawal 2016-08-26 9:37 ` Punit Agrawal 2016-08-26 12:21 ` Marc Zyngier 2016-08-26 12:21 ` Marc Zyngier 2016-08-26 12:21 ` Marc Zyngier 2016-09-01 14:55 ` Will Deacon 2016-09-01 14:55 ` Will Deacon 2016-09-01 18:29 ` Punit Agrawal 2016-09-01 18:29 ` Punit Agrawal 2016-08-16 10:45 ` Punit Agrawal [this message] 2016-08-16 10:45 ` [RFC PATCH 7/7] arm64: KVM: Enable selective trapping of " Punit Agrawal 2016-08-17 15:58 ` [RFC PATCH 0/7] Add support for monitoring guest TLB operations Paolo Bonzini 2016-08-17 15:58 ` Paolo Bonzini 2016-08-17 15:58 ` Paolo Bonzini 2016-08-17 17:01 ` Punit Agrawal 2016-08-17 17:01 ` Punit Agrawal 2016-08-17 17:01 ` Punit Agrawal 2016-08-17 17:02 ` Paolo Bonzini 2016-08-17 17:02 ` Paolo Bonzini 2016-08-17 17:20 ` Punit Agrawal 2016-08-17 17:20 ` Punit Agrawal 2016-08-18 7:04 ` Paolo Bonzini 2016-08-18 7:04 ` Paolo Bonzini
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