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Fri, 08 Oct 2021 19:13:16 -0700 (PDT) Date: Fri, 8 Oct 2021 19:12:07 -0700 In-Reply-To: <20211009021236.4122790-1-seanjc@google.com> Message-Id: <20211009021236.4122790-15-seanjc@google.com> Mime-Version: 1.0 References: <20211009021236.4122790-1-seanjc@google.com> X-Mailer: git-send-email 2.33.0.882.g93a45727a2-goog Subject: [PATCH v2 14/43] KVM: Split out a kvm_vcpu_block() helper from kvm_vcpu_halt() From: Sean Christopherson To: Marc Zyngier , Huacai Chen , Aleksandar Markovic , Paul Mackerras , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Paolo Bonzini Cc: James Morse , Alexandru Elisei , Suzuki K Poulose , Atish Patra , David Hildenbrand , Cornelia Huck , Claudio Imbrenda , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-mips@vger.kernel.org, kvm@vger.kernel.org, kvm-ppc@vger.kernel.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, David Matlack , Oliver Upton , Jing Zhang X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211008_191318_288004_281A9FC6 X-CRM114-Status: GOOD ( 14.66 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Sean Christopherson Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org Factor out the "block" part of kvm_vcpu_halt() so that x86 can emulate non-halt wait/sleep/block conditions that should not be subjected to halt-polling. No functional change intended. Reviewed-by: Christian Borntraeger Reviewed-by: David Matlack Signed-off-by: Sean Christopherson --- include/linux/kvm_host.h | 1 + virt/kvm/kvm_main.c | 52 +++++++++++++++++++++++++++------------- 2 files changed, 37 insertions(+), 16 deletions(-) diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index c2ea4004553a..2d837e06eeec 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -968,6 +968,7 @@ void kvm_sigset_activate(struct kvm_vcpu *vcpu); void kvm_sigset_deactivate(struct kvm_vcpu *vcpu); void kvm_vcpu_halt(struct kvm_vcpu *vcpu); +bool kvm_vcpu_block(struct kvm_vcpu *vcpu); void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu); void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu); bool kvm_vcpu_wake_up(struct kvm_vcpu *vcpu); diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index c13bf3367fda..42894ff7c474 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -3201,6 +3201,35 @@ static int kvm_vcpu_check_block(struct kvm_vcpu *vcpu) return ret; } +/* + * Block the vCPU until the vCPU is runnable, an event arrives, or a signal is + * pending. This is mostly used when halting a vCPU, but may also be used + * directly for other vCPU non-runnable states, e.g. x86's Wait-For-SIPI. + */ +bool kvm_vcpu_block(struct kvm_vcpu *vcpu) +{ + struct rcuwait *wait = kvm_arch_vcpu_get_wait(vcpu); + bool waited = false; + + kvm_arch_vcpu_blocking(vcpu); + + prepare_to_rcuwait(wait); + for (;;) { + set_current_state(TASK_INTERRUPTIBLE); + + if (kvm_vcpu_check_block(vcpu) < 0) + break; + + waited = true; + schedule(); + } + finish_rcuwait(wait); + + kvm_arch_vcpu_unblocking(vcpu); + + return waited; +} + static inline void update_halt_poll_stats(struct kvm_vcpu *vcpu, ktime_t start, ktime_t end, bool success) { @@ -3223,9 +3252,14 @@ static inline void update_halt_poll_stats(struct kvm_vcpu *vcpu, ktime_t start, } } +/* + * Emulate a vCPU halt condition, e.g. HLT on x86, WFI on arm, etc... If halt + * polling is enabled, busy wait for a short time before blocking to avoid the + * expensive block+unblock sequence if a wake event arrives soon after the vCPU + * is halted. + */ void kvm_vcpu_halt(struct kvm_vcpu *vcpu) { - struct rcuwait *wait = kvm_arch_vcpu_get_wait(vcpu); bool halt_poll_allowed = !kvm_arch_no_poll(vcpu); bool do_halt_poll = halt_poll_allowed && vcpu->halt_poll_ns; ktime_t start, cur, poll_end; @@ -3248,21 +3282,7 @@ void kvm_vcpu_halt(struct kvm_vcpu *vcpu) } while (kvm_vcpu_can_poll(cur, stop)); } - kvm_arch_vcpu_blocking(vcpu); - - prepare_to_rcuwait(wait); - for (;;) { - set_current_state(TASK_INTERRUPTIBLE); - - if (kvm_vcpu_check_block(vcpu) < 0) - break; - - waited = true; - schedule(); - } - finish_rcuwait(wait); - - kvm_arch_vcpu_unblocking(vcpu); + waited = kvm_vcpu_block(vcpu); cur = ktime_get(); if (waited) {