From 599275c060a02a8f0db19c2e6a70d026d4b445ca Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Wed, 21 Sep 2022 00:32:00 +0000 Subject: KVM: mips, x86: do not rely on KVM_REQ_UNHALT MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit KVM_REQ_UNHALT is a weird request that simply reports the value of kvm_arch_vcpu_runnable() on exit from kvm_vcpu_halt(). Only MIPS and x86 are looking at it, the others just clear it. Check the state of the vCPU directly so that the request is handled as a nop on all architectures. No functional change intended, except for corner cases where an event arrive immediately after a signal become pending or after another similar host-side event. Signed-off-by: Paolo Bonzini Signed-off-by: Sean Christopherson Reviewed-by: Philippe Mathieu-Daudé Message-Id: <20220921003201.1441511-12-seanjc@google.com> Signed-off-by: Paolo Bonzini --- arch/mips/kvm/emulate.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) (limited to 'arch/mips') diff --git a/arch/mips/kvm/emulate.c b/arch/mips/kvm/emulate.c index b494d8d39290..1d7c56defe93 100644 --- a/arch/mips/kvm/emulate.c +++ b/arch/mips/kvm/emulate.c @@ -955,13 +955,12 @@ enum emulation_result kvm_mips_emul_wait(struct kvm_vcpu *vcpu) kvm_vcpu_halt(vcpu); /* - * We we are runnable, then definitely go off to user space to + * We are runnable, then definitely go off to user space to * check if any I/O interrupts are pending. */ - if (kvm_check_request(KVM_REQ_UNHALT, vcpu)) { - kvm_clear_request(KVM_REQ_UNHALT, vcpu); + kvm_clear_request(KVM_REQ_UNHALT, vcpu); + if (kvm_arch_vcpu_runnable(vcpu)) vcpu->run->exit_reason = KVM_EXIT_IRQ_WINDOW_OPEN; - } } return EMULATE_DONE; -- cgit v1.2.3 From c59fb127583869350256656b7ed848c398bef879 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Wed, 21 Sep 2022 00:32:01 +0000 Subject: KVM: remove KVM_REQ_UNHALT KVM_REQ_UNHALT is now unnecessary because it is replaced by the return value of kvm_vcpu_block/kvm_vcpu_halt. Remove it. No functional change intended. Signed-off-by: Paolo Bonzini Signed-off-by: Sean Christopherson Acked-by: Marc Zyngier Message-Id: <20220921003201.1441511-13-seanjc@google.com> Signed-off-by: Paolo Bonzini --- Documentation/virt/kvm/vcpu-requests.rst | 28 +--------------------------- arch/arm64/kvm/arm.c | 1 - arch/mips/kvm/emulate.c | 1 - arch/powerpc/kvm/book3s_pr.c | 1 - arch/powerpc/kvm/book3s_pr_papr.c | 1 - arch/powerpc/kvm/booke.c | 1 - arch/powerpc/kvm/powerpc.c | 1 - arch/riscv/kvm/vcpu_insn.c | 1 - arch/s390/kvm/kvm-s390.c | 2 -- arch/x86/kvm/x86.c | 3 --- arch/x86/kvm/xen.c | 1 - include/linux/kvm_host.h | 3 +-- virt/kvm/kvm_main.c | 4 +--- 13 files changed, 3 insertions(+), 45 deletions(-) (limited to 'arch/mips') diff --git a/Documentation/virt/kvm/vcpu-requests.rst b/Documentation/virt/kvm/vcpu-requests.rst index 31f62b64e07b..87f04c1fa53d 100644 --- a/Documentation/virt/kvm/vcpu-requests.rst +++ b/Documentation/virt/kvm/vcpu-requests.rst @@ -97,7 +97,7 @@ VCPU requests are simply bit indices of the ``vcpu->requests`` bitmap. This means general bitops, like those documented in [atomic-ops]_ could also be used, e.g. :: - clear_bit(KVM_REQ_UNHALT & KVM_REQUEST_MASK, &vcpu->requests); + clear_bit(KVM_REQ_UNBLOCK & KVM_REQUEST_MASK, &vcpu->requests); However, VCPU request users should refrain from doing so, as it would break the abstraction. The first 8 bits are reserved for architecture @@ -126,17 +126,6 @@ KVM_REQ_UNBLOCK or in order to update the interrupt routing and ensure that assigned devices will wake up the vCPU. -KVM_REQ_UNHALT - - This request may be made from the KVM common function kvm_vcpu_block(), - which is used to emulate an instruction that causes a CPU to halt until - one of an architectural specific set of events and/or interrupts is - received (determined by checking kvm_arch_vcpu_runnable()). When that - event or interrupt arrives kvm_vcpu_block() makes the request. This is - in contrast to when kvm_vcpu_block() returns due to any other reason, - such as a pending signal, which does not indicate the VCPU's halt - emulation should stop, and therefore does not make the request. - KVM_REQ_OUTSIDE_GUEST_MODE This "request" ensures the target vCPU has exited guest mode prior to the @@ -297,21 +286,6 @@ architecture dependent. kvm_vcpu_block() calls kvm_arch_vcpu_runnable() to check if it should awaken. One reason to do so is to provide architectures a function where requests may be checked if necessary. -Clearing Requests ------------------ - -Generally it only makes sense for the receiving VCPU thread to clear a -request. However, in some circumstances, such as when the requesting -thread and the receiving VCPU thread are executed serially, such as when -they are the same thread, or when they are using some form of concurrency -control to temporarily execute synchronously, then it's possible to know -that the request may be cleared immediately, rather than waiting for the -receiving VCPU thread to handle the request in VCPU RUN. The only current -examples of this are kvm_vcpu_block() calls made by VCPUs to block -themselves. A possible side-effect of that call is to make the -KVM_REQ_UNHALT request, which may then be cleared immediately when the -VCPU returns from the call. - References ========== diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index 2ff0ef62abad..4f949b64fdc9 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -666,7 +666,6 @@ void kvm_vcpu_wfi(struct kvm_vcpu *vcpu) kvm_vcpu_halt(vcpu); vcpu_clear_flag(vcpu, IN_WFIT); - kvm_clear_request(KVM_REQ_UNHALT, vcpu); preempt_disable(); vgic_v4_load(vcpu); diff --git a/arch/mips/kvm/emulate.c b/arch/mips/kvm/emulate.c index 1d7c56defe93..edaec93a1a1f 100644 --- a/arch/mips/kvm/emulate.c +++ b/arch/mips/kvm/emulate.c @@ -958,7 +958,6 @@ enum emulation_result kvm_mips_emul_wait(struct kvm_vcpu *vcpu) * We are runnable, then definitely go off to user space to * check if any I/O interrupts are pending. */ - kvm_clear_request(KVM_REQ_UNHALT, vcpu); if (kvm_arch_vcpu_runnable(vcpu)) vcpu->run->exit_reason = KVM_EXIT_IRQ_WINDOW_OPEN; } diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c index d6abed6e51e6..9fc4dd8f66eb 100644 --- a/arch/powerpc/kvm/book3s_pr.c +++ b/arch/powerpc/kvm/book3s_pr.c @@ -499,7 +499,6 @@ static void kvmppc_set_msr_pr(struct kvm_vcpu *vcpu, u64 msr) if (msr & MSR_POW) { if (!vcpu->arch.pending_exceptions) { kvm_vcpu_halt(vcpu); - kvm_clear_request(KVM_REQ_UNHALT, vcpu); vcpu->stat.generic.halt_wakeup++; /* Unset POW bit after we woke up */ diff --git a/arch/powerpc/kvm/book3s_pr_papr.c b/arch/powerpc/kvm/book3s_pr_papr.c index a1f2978b2a86..b2c89e850d7a 100644 --- a/arch/powerpc/kvm/book3s_pr_papr.c +++ b/arch/powerpc/kvm/book3s_pr_papr.c @@ -393,7 +393,6 @@ int kvmppc_h_pr(struct kvm_vcpu *vcpu, unsigned long cmd) case H_CEDE: kvmppc_set_msr_fast(vcpu, kvmppc_get_msr(vcpu) | MSR_EE); kvm_vcpu_halt(vcpu); - kvm_clear_request(KVM_REQ_UNHALT, vcpu); vcpu->stat.generic.halt_wakeup++; return EMULATE_DONE; case H_LOGICAL_CI_LOAD: diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c index 06c5830a93f9..7b4920e9fd26 100644 --- a/arch/powerpc/kvm/booke.c +++ b/arch/powerpc/kvm/booke.c @@ -719,7 +719,6 @@ int kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu) if (vcpu->arch.shared->msr & MSR_WE) { local_irq_enable(); kvm_vcpu_halt(vcpu); - kvm_clear_request(KVM_REQ_UNHALT, vcpu); hard_irq_disable(); kvmppc_set_exit_type(vcpu, EMULATED_MTMSRWE_EXITS); diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c index fb1490761c87..ec9c1e3c2ff4 100644 --- a/arch/powerpc/kvm/powerpc.c +++ b/arch/powerpc/kvm/powerpc.c @@ -239,7 +239,6 @@ int kvmppc_kvm_pv(struct kvm_vcpu *vcpu) case EV_HCALL_TOKEN(EV_IDLE): r = EV_SUCCESS; kvm_vcpu_halt(vcpu); - kvm_clear_request(KVM_REQ_UNHALT, vcpu); break; default: r = EV_UNIMPLEMENTED; diff --git a/arch/riscv/kvm/vcpu_insn.c b/arch/riscv/kvm/vcpu_insn.c index 7eb90a47b571..0bb52761a3f7 100644 --- a/arch/riscv/kvm/vcpu_insn.c +++ b/arch/riscv/kvm/vcpu_insn.c @@ -191,7 +191,6 @@ void kvm_riscv_vcpu_wfi(struct kvm_vcpu *vcpu) kvm_vcpu_srcu_read_unlock(vcpu); kvm_vcpu_halt(vcpu); kvm_vcpu_srcu_read_lock(vcpu); - kvm_clear_request(KVM_REQ_UNHALT, vcpu); } } diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index edfd4bbd0cba..aa39ea4582bd 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -4343,8 +4343,6 @@ retry: goto retry; } - /* nothing to do, just clear the request */ - kvm_clear_request(KVM_REQ_UNHALT, vcpu); /* we left the vsie handler, nothing to do, just clear the request */ kvm_clear_request(KVM_REQ_VSIE_RESTART, vcpu); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 20c56be1fcf1..eb9d2c23fb04 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -10813,8 +10813,6 @@ static inline int vcpu_block(struct kvm_vcpu *vcpu) if (hv_timer) kvm_lapic_switch_to_hv_timer(vcpu); - kvm_clear_request(KVM_REQ_UNHALT, vcpu); - /* * If the vCPU is not runnable, a signal or another host event * of some kind is pending; service it without changing the @@ -11034,7 +11032,6 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu) r = 0; goto out; } - kvm_clear_request(KVM_REQ_UNHALT, vcpu); r = -EAGAIN; if (signal_pending(current)) { r = -EINTR; diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c index 280cb5dc7341..93c628d3e3a9 100644 --- a/arch/x86/kvm/xen.c +++ b/arch/x86/kvm/xen.c @@ -1065,7 +1065,6 @@ static bool kvm_xen_schedop_poll(struct kvm_vcpu *vcpu, bool longmode, del_timer(&vcpu->arch.xen.poll_timer); vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE; - kvm_clear_request(KVM_REQ_UNHALT, vcpu); } vcpu->arch.xen.poll_evtchn = 0; diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 04c7e5f2f727..32f259fa5801 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -151,12 +151,11 @@ static inline bool is_error_page(struct page *page) #define KVM_REQUEST_NO_ACTION BIT(10) /* * Architecture-independent vcpu->requests bit members - * Bits 4-7 are reserved for more arch-independent bits. + * Bits 3-7 are reserved for more arch-independent bits. */ #define KVM_REQ_TLB_FLUSH (0 | KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP) #define KVM_REQ_VM_DEAD (1 | KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP) #define KVM_REQ_UNBLOCK 2 -#define KVM_REQ_UNHALT 3 #define KVM_REQUEST_ARCH_BASE 8 /* diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index dcf47da44844..26383e63d9dd 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -3409,10 +3409,8 @@ static int kvm_vcpu_check_block(struct kvm_vcpu *vcpu) int ret = -EINTR; int idx = srcu_read_lock(&vcpu->kvm->srcu); - if (kvm_arch_vcpu_runnable(vcpu)) { - kvm_make_request(KVM_REQ_UNHALT, vcpu); + if (kvm_arch_vcpu_runnable(vcpu)) goto out; - } if (kvm_cpu_has_pending_timer(vcpu)) goto out; if (signal_pending(current)) -- cgit v1.2.3