From ef1ead0c3b1dfb43d33caa4f50c8d214f86b6bc8 Mon Sep 17 00:00:00 2001 From: David Gibson Date: Tue, 20 Dec 2016 16:48:58 +1100 Subject: KVM: PPC: Book3S HV: HPT resizing documentation and reserved numbers This adds a new powerpc-specific KVM_CAP_SPAPR_RESIZE_HPT capability to advertise whether KVM is capable of handling the PAPR extensions for resizing the hashed page table during guest runtime. It also adds definitions for two new VM ioctl()s to implement this extension, and documentation of the same. Note that, HPT resizing is already possible with KVM PR without kernel modification, since the HPT is managed within userspace (qemu). The capability defined here will only be set where an in-kernel implementation of resizing is necessary, i.e. for KVM HV. To determine if the userspace resize implementation can be used, it's necessary to check KVM_CAP_PPC_ALLOC_HTAB. Unfortunately older kernels incorrectly set KVM_CAP_PPC_ALLOC_HTAB even with KVM PR. If userspace it want to support resizing with KVM PR on such kernels, it will need a workaround. Signed-off-by: David Gibson Signed-off-by: Paul Mackerras --- include/uapi/linux/kvm.h | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'include/uapi') diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index e0035808c814..7964b970b9ad 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -685,6 +685,13 @@ struct kvm_ppc_smmu_info { struct kvm_ppc_one_seg_page_size sps[KVM_PPC_PAGE_SIZES_MAX_SZ]; }; +/* for KVM_PPC_RESIZE_HPT_{PREPARE,COMMIT} */ +struct kvm_ppc_resize_hpt { + __u64 flags; + __u32 shift; + __u32 pad; +}; + #define KVMIO 0xAE /* machine type bits, to be used as argument to KVM_CREATE_VM */ @@ -871,6 +878,7 @@ struct kvm_ppc_smmu_info { #define KVM_CAP_S390_USER_INSTR0 130 #define KVM_CAP_MSI_DEVID 131 #define KVM_CAP_PPC_HTM 132 +#define KVM_CAP_SPAPR_RESIZE_HPT 133 #define KVM_CAP_PPC_MMU_RADIX 134 #define KVM_CAP_PPC_MMU_HASH_V3 135 @@ -1189,6 +1197,9 @@ struct kvm_s390_ucas_mapping { #define KVM_ARM_SET_DEVICE_ADDR _IOW(KVMIO, 0xab, struct kvm_arm_device_addr) /* Available with KVM_CAP_PPC_RTAS */ #define KVM_PPC_RTAS_DEFINE_TOKEN _IOW(KVMIO, 0xac, struct kvm_rtas_token_args) +/* Available with KVM_CAP_SPAPR_RESIZE_HPT */ +#define KVM_PPC_RESIZE_HPT_PREPARE _IOR(KVMIO, 0xad, struct kvm_ppc_resize_hpt) +#define KVM_PPC_RESIZE_HPT_COMMIT _IOR(KVMIO, 0xae, struct kvm_ppc_resize_hpt) /* Available with KVM_CAP_PPC_RADIX_MMU or KVM_CAP_PPC_HASH_MMU_V3 */ #define KVM_PPC_CONFIGURE_V3_MMU _IOW(KVMIO, 0xaf, struct kvm_ppc_mmuv3_cfg) /* Available with KVM_CAP_PPC_RADIX_MMU */ -- cgit v1.2.3-70-g09d2 From 55dd00a73a518281bc846dc5de1a718349431eb2 Mon Sep 17 00:00:00 2001 From: Marcelo Tosatti Date: Tue, 24 Jan 2017 15:09:39 -0200 Subject: KVM: x86: add KVM_HC_CLOCK_PAIRING hypercall Add a hypercall to retrieve the host realtime clock and the TSC value used to calculate that clock read. Used to implement clock synchronization between host and guest. Signed-off-by: Marcelo Tosatti Signed-off-by: Paolo Bonzini --- Documentation/virtual/kvm/hypercalls.txt | 35 +++++++++++++++++ arch/x86/include/uapi/asm/kvm_para.h | 9 +++++ arch/x86/kvm/x86.c | 66 ++++++++++++++++++++++++++++++++ include/uapi/linux/kvm_para.h | 2 + 4 files changed, 112 insertions(+) (limited to 'include/uapi') diff --git a/Documentation/virtual/kvm/hypercalls.txt b/Documentation/virtual/kvm/hypercalls.txt index c8d040e27046..feaaa634f154 100644 --- a/Documentation/virtual/kvm/hypercalls.txt +++ b/Documentation/virtual/kvm/hypercalls.txt @@ -81,3 +81,38 @@ the vcpu to sleep until occurrence of an appropriate event. Another vcpu of the same guest can wakeup the sleeping vcpu by issuing KVM_HC_KICK_CPU hypercall, specifying APIC ID (a1) of the vcpu to be woken up. An additional argument (a0) is used in the hypercall for future use. + + +6. KVM_HC_CLOCK_PAIRING +------------------------ +Architecture: x86 +Status: active +Purpose: Hypercall used to synchronize host and guest clocks. +Usage: + +a0: guest physical address where host copies +"struct kvm_clock_offset" structure. + +a1: clock_type, ATM only KVM_CLOCK_PAIRING_WALLCLOCK (0) +is supported (corresponding to the host's CLOCK_REALTIME clock). + + struct kvm_clock_pairing { + __s64 sec; + __s64 nsec; + __u64 tsc; + __u32 flags; + __u32 pad[9]; + }; + + Where: + * sec: seconds from clock_type clock. + * nsec: nanoseconds from clock_type clock. + * tsc: guest TSC value used to calculate sec/nsec pair + * flags: flags, unused (0) at the moment. + +The hypercall lets a guest compute a precise timestamp across +host and guest. The guest can use the returned TSC value to +compute the CLOCK_REALTIME for its clock, at the same instant. + +Returns KVM_EOPNOTSUPP if the host does not use TSC clocksource, +or if clock type is different than KVM_CLOCK_PAIRING_WALLCLOCK. diff --git a/arch/x86/include/uapi/asm/kvm_para.h b/arch/x86/include/uapi/asm/kvm_para.h index 1421a6585126..cff0bb6556f8 100644 --- a/arch/x86/include/uapi/asm/kvm_para.h +++ b/arch/x86/include/uapi/asm/kvm_para.h @@ -50,6 +50,15 @@ struct kvm_steal_time { __u32 pad[11]; }; +#define KVM_CLOCK_PAIRING_WALLCLOCK 0 +struct kvm_clock_pairing { + __s64 sec; + __s64 nsec; + __u64 tsc; + __u32 flags; + __u32 pad[9]; +}; + #define KVM_STEAL_ALIGNMENT_BITS 5 #define KVM_STEAL_VALID_BITS ((-1ULL << (KVM_STEAL_ALIGNMENT_BITS + 1))) #define KVM_STEAL_RESERVED_MASK (((1 << KVM_STEAL_ALIGNMENT_BITS) - 1 ) << 1) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 4fd4d4f35caf..09e5d31dac98 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1142,6 +1142,7 @@ struct pvclock_gtod_data { u64 boot_ns; u64 nsec_base; + u64 wall_time_sec; }; static struct pvclock_gtod_data pvclock_gtod_data; @@ -1165,6 +1166,8 @@ static void update_pvclock_gtod(struct timekeeper *tk) vdata->boot_ns = boot_ns; vdata->nsec_base = tk->tkr_mono.xtime_nsec; + vdata->wall_time_sec = tk->xtime_sec; + write_seqcount_end(&vdata->seq); } #endif @@ -1626,6 +1629,28 @@ static int do_monotonic_boot(s64 *t, u64 *cycle_now) return mode; } +static int do_realtime(struct timespec *ts, u64 *cycle_now) +{ + struct pvclock_gtod_data *gtod = &pvclock_gtod_data; + unsigned long seq; + int mode; + u64 ns; + + do { + seq = read_seqcount_begin(>od->seq); + mode = gtod->clock.vclock_mode; + ts->tv_sec = gtod->wall_time_sec; + ns = gtod->nsec_base; + ns += vgettsc(cycle_now); + ns >>= gtod->clock.shift; + } while (unlikely(read_seqcount_retry(>od->seq, seq))); + + ts->tv_sec += __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns); + ts->tv_nsec = ns; + + return mode; +} + /* returns true if host is using tsc clocksource */ static bool kvm_get_time_and_clockread(s64 *kernel_ns, u64 *cycle_now) { @@ -1635,6 +1660,17 @@ static bool kvm_get_time_and_clockread(s64 *kernel_ns, u64 *cycle_now) return do_monotonic_boot(kernel_ns, cycle_now) == VCLOCK_TSC; } + +/* returns true if host is using tsc clocksource */ +static bool kvm_get_walltime_and_clockread(struct timespec *ts, + u64 *cycle_now) +{ + /* checked again under seqlock below */ + if (pvclock_gtod_data.clock.vclock_mode != VCLOCK_TSC) + return false; + + return do_realtime(ts, cycle_now) == VCLOCK_TSC; +} #endif /* @@ -6112,6 +6148,33 @@ int kvm_emulate_halt(struct kvm_vcpu *vcpu) } EXPORT_SYMBOL_GPL(kvm_emulate_halt); +static int kvm_pv_clock_pairing(struct kvm_vcpu *vcpu, gpa_t paddr, + unsigned long clock_type) +{ + struct kvm_clock_pairing clock_pairing; + struct timespec ts; + cycle_t cycle; + int ret; + + if (clock_type != KVM_CLOCK_PAIRING_WALLCLOCK) + return -KVM_EOPNOTSUPP; + + if (kvm_get_walltime_and_clockread(&ts, &cycle) == false) + return -KVM_EOPNOTSUPP; + + clock_pairing.sec = ts.tv_sec; + clock_pairing.nsec = ts.tv_nsec; + clock_pairing.tsc = kvm_read_l1_tsc(vcpu, cycle); + clock_pairing.flags = 0; + + ret = 0; + if (kvm_write_guest(vcpu->kvm, paddr, &clock_pairing, + sizeof(struct kvm_clock_pairing))) + ret = -KVM_EFAULT; + + return ret; +} + /* * kvm_pv_kick_cpu_op: Kick a vcpu. * @@ -6176,6 +6239,9 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu) kvm_pv_kick_cpu_op(vcpu->kvm, a0, a1); ret = 0; break; + case KVM_HC_CLOCK_PAIRING: + ret = kvm_pv_clock_pairing(vcpu, a0, a1); + break; default: ret = -KVM_ENOSYS; break; diff --git a/include/uapi/linux/kvm_para.h b/include/uapi/linux/kvm_para.h index bf6cd7d5cac2..fed506aeff62 100644 --- a/include/uapi/linux/kvm_para.h +++ b/include/uapi/linux/kvm_para.h @@ -14,6 +14,7 @@ #define KVM_EFAULT EFAULT #define KVM_E2BIG E2BIG #define KVM_EPERM EPERM +#define KVM_EOPNOTSUPP 95 #define KVM_HC_VAPIC_POLL_IRQ 1 #define KVM_HC_MMU_OP 2 @@ -23,6 +24,7 @@ #define KVM_HC_MIPS_GET_CLOCK_FREQ 6 #define KVM_HC_MIPS_EXIT_VM 7 #define KVM_HC_MIPS_CONSOLE_OUTPUT 8 +#define KVM_HC_CLOCK_PAIRING 9 /* * hypercalls use architecture specific -- cgit v1.2.3-70-g09d2 From 460df4c1fc7c00829050c08d6368dc6e6beef307 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Wed, 8 Feb 2017 11:50:15 +0100 Subject: KVM: race-free exit from KVM_RUN without POSIX signals MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The purpose of the KVM_SET_SIGNAL_MASK API is to let userspace "kick" a VCPU out of KVM_RUN through a POSIX signal. A signal is attached to a dummy signal handler; by blocking the signal outside KVM_RUN and unblocking it inside, this possible race is closed: VCPU thread service thread -------------------------------------------------------------- check flag set flag raise signal (signal handler does nothing) KVM_RUN However, one issue with KVM_SET_SIGNAL_MASK is that it has to take tsk->sighand->siglock on every KVM_RUN. This lock is often on a remote NUMA node, because it is on the node of a thread's creator. Taking this lock can be very expensive if there are many userspace exits (as is the case for SMP Windows VMs without Hyper-V reference time counter). As an alternative, we can put the flag directly in kvm_run so that KVM can see it: VCPU thread service thread -------------------------------------------------------------- raise signal signal handler set run->immediate_exit KVM_RUN check run->immediate_exit Reviewed-by: Radim Krčmář Reviewed-by: David Hildenbrand Signed-off-by: Paolo Bonzini --- Documentation/virtual/kvm/api.txt | 13 ++++++++++++- arch/arm/kvm/arm.c | 4 ++++ arch/mips/kvm/mips.c | 7 ++++++- arch/powerpc/kvm/powerpc.c | 6 +++++- arch/s390/kvm/kvm-s390.c | 4 ++++ arch/x86/kvm/x86.c | 6 +++++- include/uapi/linux/kvm.h | 4 +++- 7 files changed, 39 insertions(+), 5 deletions(-) (limited to 'include/uapi') diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index e4f2cdcf78eb..069450938b79 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -3389,7 +3389,18 @@ struct kvm_run { Request that KVM_RUN return when it becomes possible to inject external interrupts into the guest. Useful in conjunction with KVM_INTERRUPT. - __u8 padding1[7]; + __u8 immediate_exit; + +This field is polled once when KVM_RUN starts; if non-zero, KVM_RUN +exits immediately, returning -EINTR. In the common scenario where a +signal is used to "kick" a VCPU out of KVM_RUN, this field can be used +to avoid usage of KVM_SET_SIGNAL_MASK, which has worse scalability. +Rather than blocking the signal outside KVM_RUN, userspace can set up +a signal handler that sets run->immediate_exit to a non-zero value. + +This field is ignored if KVM_CAP_IMMEDIATE_EXIT is not available. + + __u8 padding1[6]; /* out */ __u32 exit_reason; diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c index 21c493a9e5c9..c9a2103faeb9 100644 --- a/arch/arm/kvm/arm.c +++ b/arch/arm/kvm/arm.c @@ -206,6 +206,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) case KVM_CAP_ARM_PSCI_0_2: case KVM_CAP_READONLY_MEM: case KVM_CAP_MP_STATE: + case KVM_CAP_IMMEDIATE_EXIT: r = 1; break; case KVM_CAP_COALESCED_MMIO: @@ -604,6 +605,9 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run) return ret; } + if (run->immediate_exit) + return -EINTR; + if (vcpu->sigset_active) sigprocmask(SIG_SETMASK, &vcpu->sigset, &sigsaved); diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c index 31ee5ee0010b..ed81e5ac1426 100644 --- a/arch/mips/kvm/mips.c +++ b/arch/mips/kvm/mips.c @@ -397,7 +397,7 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu, int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run) { - int r = 0; + int r = -EINTR; sigset_t sigsaved; if (vcpu->sigset_active) @@ -409,6 +409,9 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run) vcpu->mmio_needed = 0; } + if (run->immediate_exit) + goto out; + lose_fpu(1); local_irq_disable(); @@ -429,6 +432,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run) guest_exit_irqoff(); local_irq_enable(); +out: if (vcpu->sigset_active) sigprocmask(SIG_SETMASK, &sigsaved, NULL); @@ -1021,6 +1025,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) case KVM_CAP_ENABLE_CAP: case KVM_CAP_READONLY_MEM: case KVM_CAP_SYNC_MMU: + case KVM_CAP_IMMEDIATE_EXIT: r = 1; break; case KVM_CAP_COALESCED_MMIO: diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c index 2b3e4e620078..1fe1391ba2c2 100644 --- a/arch/powerpc/kvm/powerpc.c +++ b/arch/powerpc/kvm/powerpc.c @@ -511,6 +511,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) case KVM_CAP_ONE_REG: case KVM_CAP_IOEVENTFD: case KVM_CAP_DEVICE_CTRL: + case KVM_CAP_IMMEDIATE_EXIT: r = 1; break; case KVM_CAP_PPC_PAIRED_SINGLES: @@ -1117,7 +1118,10 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run) #endif } - r = kvmppc_vcpu_run(run, vcpu); + if (run->immediate_exit) + r = -EINTR; + else + r = kvmppc_vcpu_run(run, vcpu); if (vcpu->sigset_active) sigprocmask(SIG_SETMASK, &sigsaved, NULL); diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 502de74ea984..99e35fe0dea8 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -370,6 +370,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) case KVM_CAP_S390_IRQCHIP: case KVM_CAP_VM_ATTRIBUTES: case KVM_CAP_MP_STATE: + case KVM_CAP_IMMEDIATE_EXIT: case KVM_CAP_S390_INJECT_IRQ: case KVM_CAP_S390_USER_SIGP: case KVM_CAP_S390_USER_STSI: @@ -2798,6 +2799,9 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run) int rc; sigset_t sigsaved; + if (kvm_run->immediate_exit) + return -EINTR; + if (guestdbg_exit_pending(vcpu)) { kvm_s390_prepare_debug_exit(vcpu); return 0; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 0aa8db229e0a..8d3047c8cce7 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2672,6 +2672,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) case KVM_CAP_DISABLE_QUIRKS: case KVM_CAP_SET_BOOT_CPU_ID: case KVM_CAP_SPLIT_IRQCHIP: + case KVM_CAP_IMMEDIATE_EXIT: #ifdef CONFIG_KVM_DEVICE_ASSIGNMENT case KVM_CAP_ASSIGN_DEV_IRQ: case KVM_CAP_PCI_2_3: @@ -7202,7 +7203,10 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run) } else WARN_ON(vcpu->arch.pio.count || vcpu->mmio_needed); - r = vcpu_run(vcpu); + if (kvm_run->immediate_exit) + r = -EINTR; + else + r = vcpu_run(vcpu); out: post_kvm_run_save(vcpu); diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 7964b970b9ad..f51d5082a377 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -218,7 +218,8 @@ struct kvm_hyperv_exit { struct kvm_run { /* in */ __u8 request_interrupt_window; - __u8 padding1[7]; + __u8 immediate_exit; + __u8 padding1[6]; /* out */ __u32 exit_reason; @@ -881,6 +882,7 @@ struct kvm_ppc_resize_hpt { #define KVM_CAP_SPAPR_RESIZE_HPT 133 #define KVM_CAP_PPC_MMU_RADIX 134 #define KVM_CAP_PPC_MMU_HASH_V3 135 +#define KVM_CAP_IMMEDIATE_EXIT 136 #ifdef KVM_CAP_IRQ_ROUTING -- cgit v1.2.3-70-g09d2