From: Steven Price <steven.price@arm.com> Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Catalin Marinas <catalin.marinas@arm.com>, linux-doc@vger.kernel.org, Russell King <linux@armlinux.org.uk>, Steven Price <steven.price@arm.com>, linux-arm-kernel@lists.infradead.org, Marc Zyngier <maz@kernel.org>, Paolo Bonzini <pbonzini@redhat.com>, Will Deacon <will@kernel.org>, kvmarm@lists.cs.columbia.edu Subject: [PATCH 9/9] arm64: Retrieve stolen time as paravirtualized guest Date: Fri, 2 Aug 2019 15:50:17 +0100 Message-ID: <20190802145017.42543-10-steven.price@arm.com> (raw) In-Reply-To: <20190802145017.42543-1-steven.price@arm.com> Enable paravirtualization features when running under a hypervisor supporting the PV_TIME_ST hypercall. For each (v)CPU, we ask the hypervisor for the location of a shared page which the hypervisor will use to report stolen time to us. We set pv_time_ops to the stolen time function which simply reads the stolen value from the shared page for a VCPU. We guarantee single-copy atomicity using READ_ONCE which means we can also read the stolen time for another VCPU than the currently running one while it is potentially being updated by the hypervisor. Signed-off-by: Steven Price <steven.price@arm.com> --- arch/arm64/kernel/Makefile | 1 + arch/arm64/kernel/kvm.c | 155 +++++++++++++++++++++++++++++++++++++ include/linux/cpuhotplug.h | 1 + 3 files changed, 157 insertions(+) create mode 100644 arch/arm64/kernel/kvm.c diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile index 478491f07b4f..eb36edf9b930 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -63,6 +63,7 @@ obj-$(CONFIG_CRASH_CORE) += crash_core.o obj-$(CONFIG_ARM_SDE_INTERFACE) += sdei.o obj-$(CONFIG_ARM64_SSBD) += ssbd.o obj-$(CONFIG_ARM64_PTR_AUTH) += pointer_auth.o +obj-$(CONFIG_PARAVIRT) += kvm.o obj-y += vdso/ probes/ obj-$(CONFIG_COMPAT_VDSO) += vdso32/ diff --git a/arch/arm64/kernel/kvm.c b/arch/arm64/kernel/kvm.c new file mode 100644 index 000000000000..245398c79dae --- /dev/null +++ b/arch/arm64/kernel/kvm.c @@ -0,0 +1,155 @@ +// SPDX-License-Identifier: GPL-2.0 +// Copyright (C) 2019 Arm Ltd. + +#define pr_fmt(fmt) "kvmarm-pv: " fmt + +#include <linux/arm-smccc.h> +#include <linux/cpuhotplug.h> +#include <linux/io.h> +#include <linux/printk.h> +#include <linux/psci.h> +#include <linux/reboot.h> +#include <linux/slab.h> + +#include <asm/paravirt.h> +#include <asm/pvclock-abi.h> +#include <asm/smp_plat.h> + +struct kvmarm_stolen_time_region { + struct pvclock_vcpu_stolen_time_info *kaddr; +}; + +static DEFINE_PER_CPU(struct kvmarm_stolen_time_region, stolen_time_region); + +static bool steal_acc = true; +static int __init parse_no_stealacc(char *arg) +{ + steal_acc = false; + return 0; +} +early_param("no-steal-acc", parse_no_stealacc); + +/* return stolen time in ns by asking the hypervisor */ +static u64 kvm_steal_clock(int cpu) +{ + struct kvmarm_stolen_time_region *reg; + + reg = per_cpu_ptr(&stolen_time_region, cpu); + if (!reg->kaddr) { + pr_warn_once("stolen time enabled but not configured for cpu %d\n", + cpu); + return 0; + } + + return le64_to_cpu(READ_ONCE(reg->kaddr->stolen_time)); +} + +static int disable_stolen_time_current_cpu(void) +{ + struct kvmarm_stolen_time_region *reg; + + reg = this_cpu_ptr(&stolen_time_region); + if (!reg->kaddr) + return 0; + + memunmap(reg->kaddr); + memset(reg, 0, sizeof(*reg)); + + return 0; +} + +static int stolen_time_dying_cpu(unsigned int cpu) +{ + return disable_stolen_time_current_cpu(); +} + +static int init_stolen_time_cpu(unsigned int cpu) +{ + struct kvmarm_stolen_time_region *reg; + struct arm_smccc_res res; + + reg = this_cpu_ptr(&stolen_time_region); + + if (reg->kaddr) + return 0; + + arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_TIME_ST, &res); + + if ((long)res.a0 < 0) + return -EINVAL; + + reg->kaddr = memremap(res.a0, + sizeof(struct pvclock_vcpu_stolen_time_info), + MEMREMAP_WB); + + if (reg->kaddr == NULL) { + pr_warn("Failed to map stolen time data structure\n"); + return -EINVAL; + } + + if (le32_to_cpu(reg->kaddr->revision) != 0 || + le32_to_cpu(reg->kaddr->attributes) != 0) { + pr_warn("Unexpected revision or attributes in stolen time data\n"); + return -ENXIO; + } + + return 0; +} + +static int kvm_arm_init_stolen_time(void) +{ + int ret; + + ret = cpuhp_setup_state(CPUHP_AP_ARM_KVMPV_STARTING, + "hypervisor/kvmarm/pv:starting", + init_stolen_time_cpu, stolen_time_dying_cpu); + if (ret < 0) + return ret; + return 0; +} + +static bool has_kvm_steal_clock(void) +{ + struct arm_smccc_res res; + + /* To detect the presence of PV time support we require SMCCC 1.1+ */ + if (psci_ops.smccc_version < SMCCC_VERSION_1_1) + return false; + + arm_smccc_1_1_invoke(ARM_SMCCC_ARCH_FEATURES_FUNC_ID, + ARM_SMCCC_HV_PV_FEATURES, &res); + + if (res.a0 != SMCCC_RET_SUCCESS) + return false; + + arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_FEATURES, + ARM_SMCCC_HV_PV_TIME_ST, &res); + + if (res.a0 != SMCCC_RET_SUCCESS) + return false; + + return true; +} + +static int __init kvm_guest_init(void) +{ + int ret = 0; + + if (!has_kvm_steal_clock()) + return 0; + + ret = kvm_arm_init_stolen_time(); + if (ret) + return ret; + + pv_ops.time.steal_clock = kvm_steal_clock; + + static_key_slow_inc(¶virt_steal_enabled); + if (steal_acc) + static_key_slow_inc(¶virt_steal_rq_enabled); + + pr_info("using stolen time PV\n"); + + return 0; +} +early_initcall(kvm_guest_init); diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h index 068793a619ca..89d75edb5750 100644 --- a/include/linux/cpuhotplug.h +++ b/include/linux/cpuhotplug.h @@ -136,6 +136,7 @@ enum cpuhp_state { /* Must be the last timer callback */ CPUHP_AP_DUMMY_TIMER_STARTING, CPUHP_AP_ARM_XEN_STARTING, + CPUHP_AP_ARM_KVMPV_STARTING, CPUHP_AP_ARM_CORESIGHT_STARTING, CPUHP_AP_ARM64_ISNDEP_STARTING, CPUHP_AP_SMPCFD_DYING, -- 2.20.1 _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
next prev parent reply index Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-08-02 14:50 [PATCH 0/9] arm64: Stolen time support Steven Price 2019-08-02 14:50 ` [PATCH 1/9] KVM: arm64: Document PV-time interface Steven Price 2019-08-03 11:13 ` Marc Zyngier 2019-08-05 13:06 ` Steven Price 2019-08-05 3:23 ` Zenghui Yu 2019-08-05 13:06 ` Steven Price 2019-08-05 16:40 ` Christophe de Dinechin 2019-08-07 13:21 ` Steven Price 2019-08-07 14:28 ` Christophe de Dinechin 2019-08-07 15:26 ` Steven Price 2019-08-02 14:50 ` [PATCH 2/9] KVM: arm/arm64: Factor out hypercall handling from PSCI code Steven Price 2019-08-02 14:50 ` [PATCH 3/9] KVM: arm64: Implement PV_FEATURES call Steven Price 2019-08-03 11:21 ` Marc Zyngier 2019-08-05 13:14 ` Steven Price 2019-08-02 14:50 ` [PATCH 4/9] KVM: arm64: Support stolen time reporting via shared structure Steven Price 2019-08-03 11:55 ` Marc Zyngier 2019-08-05 14:09 ` Steven Price 2019-08-03 17:58 ` Marc Zyngier 2019-08-03 18:13 ` Marc Zyngier 2019-08-05 14:18 ` Steven Price 2019-08-02 14:50 ` [PATCH 5/9] KVM: Allow kvm_device_ops to be const Steven Price 2019-08-02 14:50 ` [PATCH 6/9] KVM: arm64: Provide a PV_TIME device to user space Steven Price 2019-08-03 12:51 ` Marc Zyngier 2019-08-03 17:34 ` Marc Zyngier 2019-08-07 13:39 ` Steven Price 2019-08-07 13:51 ` Marc Zyngier 2019-08-05 16:10 ` Steven Price 2019-08-05 16:28 ` Marc Zyngier 2019-08-02 14:50 ` [PATCH 7/9] arm/arm64: Provide a wrapper for SMCCC 1.1 calls Steven Price 2019-08-05 10:03 ` Will Deacon 2019-08-02 14:50 ` [PATCH 8/9] arm/arm64: Make use of the SMCCC 1.1 wrapper Steven Price 2019-08-02 14:50 ` Steven Price [this message] 2019-08-04 9:53 ` [PATCH 9/9] arm64: Retrieve stolen time as paravirtualized guest Marc Zyngier 2019-08-08 15:29 ` Steven Price 2019-08-08 15:49 ` Marc Zyngier 2019-08-09 13:51 ` Zenghui Yu 2019-08-12 10:39 ` Steven Price 2019-08-13 6:06 ` Zenghui Yu 2019-08-03 18:05 ` [PATCH 0/9] arm64: Stolen time support Marc Zyngier 2019-08-05 13:06 ` Steven Price 2019-08-05 13:26 ` Marc Zyngier 2019-08-14 13:02 ` Alexander Graf 2019-08-14 14:19 ` Marc Zyngier 2019-08-14 14:52 ` [UNVERIFIED SENDER] " Alexander Graf 2019-08-16 10:23 ` Steven Price 2020-07-21 3:26 ` zhukeqian 2020-07-27 10:48 ` Steven Price 2020-07-29 2:57 ` zhukeqian
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