From patchwork Mon Jun 22 22:42:35 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sean Christopherson X-Patchwork-Id: 11619329 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id A6D0913A0 for ; Mon, 22 Jun 2020 22:45:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9050A2073E for ; Mon, 22 Jun 2020 22:45:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731589AbgFVWpd (ORCPT ); Mon, 22 Jun 2020 18:45:33 -0400 Received: from mga18.intel.com ([134.134.136.126]:27425 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730785AbgFVWmy (ORCPT ); Mon, 22 Jun 2020 18:42:54 -0400 IronPort-SDR: G6SSKvUj6zHHGtv7PjRMcnMXFEy8oKPMkQlbnxl37s19r/DZUdkAxmJ5MdxVV0dT3pqrY9G9Lv STxQo3RbZURg== X-IronPort-AV: E=McAfee;i="6000,8403,9660"; a="131303561" X-IronPort-AV: E=Sophos;i="5.75,268,1589266800"; d="scan'208";a="131303561" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Jun 2020 15:42:51 -0700 IronPort-SDR: Dl8zm+EQRZM85TtvD8EIwG92M6HXrFkskY7uvVjO5nZcuTdxX1e49dv9KEePjG6D9bqzoO5tr+ UhJzx6KWATRw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.75,268,1589266800"; d="scan'208";a="264634901" Received: from sjchrist-coffee.jf.intel.com ([10.54.74.152]) by fmsmga008.fm.intel.com with ESMTP; 22 Jun 2020 15:42:50 -0700 From: Sean Christopherson To: Paolo Bonzini Cc: Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 01/15] KVM: x86: Rename "shared_msrs" to "user_return_msrs" Date: Mon, 22 Jun 2020 15:42:35 -0700 Message-Id: <20200622224249.29562-2-sean.j.christopherson@intel.com> X-Mailer: git-send-email 2.26.0 In-Reply-To: <20200622224249.29562-1-sean.j.christopherson@intel.com> References: <20200622224249.29562-1-sean.j.christopherson@intel.com> MIME-Version: 1.0 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Rename the "shared_msrs" mechanism, which is used to defer restoring MSRs that are only consumed when running in userspace, to a more banal but less likely to be confusing "user_return_msrs". The "shared" nomenclature is confusing as it's not obvious who is sharing what, e.g. reasonable interpretations are that the guest value is shared by vCPUs in a VM, or that the MSR value is shared/common to guest and host, both of which are wrong. "shared" is also misleading as the MSR value (in hardware) is not guaranteed to be shared/reused between VMs (if that's indeed the correct interpretation of the name), as the ability to share values between VMs is simply a side effect (albiet a very nice side effect) of deferring restoration of the host value until returning from userspace. "user_return" avoids the above confusion by describing the mechanism itself instead of its effects. Signed-off-by: Sean Christopherson --- arch/x86/include/asm/kvm_host.h | 4 +- arch/x86/kvm/vmx/vmx.c | 11 ++-- arch/x86/kvm/x86.c | 101 +++++++++++++++++--------------- 3 files changed, 60 insertions(+), 56 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index f8998e97457f..65a2c442bad7 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1656,8 +1656,8 @@ int kvm_pv_send_ipi(struct kvm *kvm, unsigned long ipi_bitmap_low, unsigned long ipi_bitmap_high, u32 min, unsigned long icr, int op_64_bit); -void kvm_define_shared_msr(unsigned index, u32 msr); -int kvm_set_shared_msr(unsigned index, u64 val, u64 mask); +void kvm_define_user_return_msr(unsigned index, u32 msr); +int kvm_set_user_return_msr(unsigned index, u64 val, u64 mask); u64 kvm_scale_tsc(struct kvm_vcpu *vcpu, u64 tsc); u64 kvm_read_l1_tsc(struct kvm_vcpu *vcpu, u64 host_tsc); diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 08e26a9518c2..ea79a02d905c 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -653,8 +653,7 @@ static int vmx_set_guest_msr(struct vcpu_vmx *vmx, struct shared_msr_entry *msr, msr->data = data; if (msr - vmx->guest_msrs < vmx->save_nmsrs) { preempt_disable(); - ret = kvm_set_shared_msr(msr->index, msr->data, - msr->mask); + ret = kvm_set_user_return_msr(msr->index, msr->data, msr->mask); preempt_enable(); if (ret) msr->data = old_msr_data; @@ -1146,9 +1145,9 @@ void vmx_prepare_switch_to_guest(struct kvm_vcpu *vcpu) if (!vmx->guest_msrs_ready) { vmx->guest_msrs_ready = true; for (i = 0; i < vmx->save_nmsrs; ++i) - kvm_set_shared_msr(vmx->guest_msrs[i].index, - vmx->guest_msrs[i].data, - vmx->guest_msrs[i].mask); + kvm_set_user_return_msr(vmx->guest_msrs[i].index, + vmx->guest_msrs[i].data, + vmx->guest_msrs[i].mask); } @@ -8002,7 +8001,7 @@ static __init int hardware_setup(void) host_idt_base = dt.address; for (i = 0; i < ARRAY_SIZE(vmx_msr_index); ++i) - kvm_define_shared_msr(i, vmx_msr_index[i]); + kvm_define_user_return_msr(i, vmx_msr_index[i]); if (setup_vmcs_config(&vmcs_config, &vmx_capability) < 0) return -EIO; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 00c88c2f34e4..098b10ab2993 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -160,24 +160,29 @@ module_param(force_emulation_prefix, bool, S_IRUGO); int __read_mostly pi_inject_timer = -1; module_param(pi_inject_timer, bint, S_IRUGO | S_IWUSR); -#define KVM_NR_SHARED_MSRS 16 +/* + * Restoring the host value for MSRs that are only consumed when running in + * usermode, e.g. SYSCALL MSRs and TSC_AUX, can be deferred until the CPU + * returns to userspace, i.e. the kernel can run with the guest's value. + */ +#define KVM_MAX_NR_USER_RETURN_MSRS 16 -struct kvm_shared_msrs_global { +struct kvm_user_return_msrs_global { int nr; - u32 msrs[KVM_NR_SHARED_MSRS]; + u32 msrs[KVM_MAX_NR_USER_RETURN_MSRS]; }; -struct kvm_shared_msrs { +struct kvm_user_return_msrs { struct user_return_notifier urn; bool registered; - struct kvm_shared_msr_values { + struct kvm_user_return_msr_values { u64 host; u64 curr; - } values[KVM_NR_SHARED_MSRS]; + } values[KVM_MAX_NR_USER_RETURN_MSRS]; }; -static struct kvm_shared_msrs_global __read_mostly shared_msrs_global; -static struct kvm_shared_msrs __percpu *shared_msrs; +static struct kvm_user_return_msrs_global __read_mostly user_return_msrs_global; +static struct kvm_user_return_msrs __percpu *user_return_msrs; #define KVM_SUPPORTED_XCR0 (XFEATURE_MASK_FP | XFEATURE_MASK_SSE \ | XFEATURE_MASK_YMM | XFEATURE_MASK_BNDREGS \ @@ -266,9 +271,9 @@ static inline void kvm_async_pf_hash_reset(struct kvm_vcpu *vcpu) static void kvm_on_user_return(struct user_return_notifier *urn) { unsigned slot; - struct kvm_shared_msrs *locals - = container_of(urn, struct kvm_shared_msrs, urn); - struct kvm_shared_msr_values *values; + struct kvm_user_return_msrs *msrs + = container_of(urn, struct kvm_user_return_msrs, urn); + struct kvm_user_return_msr_values *values; unsigned long flags; /* @@ -276,73 +281,73 @@ static void kvm_on_user_return(struct user_return_notifier *urn) * interrupted and executed through kvm_arch_hardware_disable() */ local_irq_save(flags); - if (locals->registered) { - locals->registered = false; + if (msrs->registered) { + msrs->registered = false; user_return_notifier_unregister(urn); } local_irq_restore(flags); - for (slot = 0; slot < shared_msrs_global.nr; ++slot) { - values = &locals->values[slot]; + for (slot = 0; slot < user_return_msrs_global.nr; ++slot) { + values = &msrs->values[slot]; if (values->host != values->curr) { - wrmsrl(shared_msrs_global.msrs[slot], values->host); + wrmsrl(user_return_msrs_global.msrs[slot], values->host); values->curr = values->host; } } } -void kvm_define_shared_msr(unsigned slot, u32 msr) +void kvm_define_user_return_msr(unsigned slot, u32 msr) { - BUG_ON(slot >= KVM_NR_SHARED_MSRS); - shared_msrs_global.msrs[slot] = msr; - if (slot >= shared_msrs_global.nr) - shared_msrs_global.nr = slot + 1; + BUG_ON(slot >= KVM_MAX_NR_USER_RETURN_MSRS); + user_return_msrs_global.msrs[slot] = msr; + if (slot >= user_return_msrs_global.nr) + user_return_msrs_global.nr = slot + 1; } -EXPORT_SYMBOL_GPL(kvm_define_shared_msr); +EXPORT_SYMBOL_GPL(kvm_define_user_return_msr); -static void kvm_shared_msr_cpu_online(void) +static void kvm_user_return_msr_cpu_online(void) { unsigned int cpu = smp_processor_id(); - struct kvm_shared_msrs *smsr = per_cpu_ptr(shared_msrs, cpu); + struct kvm_user_return_msrs *msrs = per_cpu_ptr(user_return_msrs, cpu); u64 value; int i; - for (i = 0; i < shared_msrs_global.nr; ++i) { - rdmsrl_safe(shared_msrs_global.msrs[i], &value); - smsr->values[i].host = value; - smsr->values[i].curr = value; + for (i = 0; i < user_return_msrs_global.nr; ++i) { + rdmsrl_safe(user_return_msrs_global.msrs[i], &value); + msrs->values[i].host = value; + msrs->values[i].curr = value; } } -int kvm_set_shared_msr(unsigned slot, u64 value, u64 mask) +int kvm_set_user_return_msr(unsigned slot, u64 value, u64 mask) { unsigned int cpu = smp_processor_id(); - struct kvm_shared_msrs *smsr = per_cpu_ptr(shared_msrs, cpu); + struct kvm_user_return_msrs *msrs = per_cpu_ptr(user_return_msrs, cpu); int err; - value = (value & mask) | (smsr->values[slot].host & ~mask); - if (value == smsr->values[slot].curr) + value = (value & mask) | (msrs->values[slot].host & ~mask); + if (value == msrs->values[slot].curr) return 0; - err = wrmsrl_safe(shared_msrs_global.msrs[slot], value); + err = wrmsrl_safe(user_return_msrs_global.msrs[slot], value); if (err) return 1; - smsr->values[slot].curr = value; - if (!smsr->registered) { - smsr->urn.on_user_return = kvm_on_user_return; - user_return_notifier_register(&smsr->urn); - smsr->registered = true; + msrs->values[slot].curr = value; + if (!msrs->registered) { + msrs->urn.on_user_return = kvm_on_user_return; + user_return_notifier_register(&msrs->urn); + msrs->registered = true; } return 0; } -EXPORT_SYMBOL_GPL(kvm_set_shared_msr); +EXPORT_SYMBOL_GPL(kvm_set_user_return_msr); static void drop_user_return_notifiers(void) { unsigned int cpu = smp_processor_id(); - struct kvm_shared_msrs *smsr = per_cpu_ptr(shared_msrs, cpu); + struct kvm_user_return_msrs *msrs = per_cpu_ptr(user_return_msrs, cpu); - if (smsr->registered) - kvm_on_user_return(&smsr->urn); + if (msrs->registered) + kvm_on_user_return(&msrs->urn); } u64 kvm_get_apic_base(struct kvm_vcpu *vcpu) @@ -7465,9 +7470,9 @@ int kvm_arch_init(void *opaque) goto out_free_x86_fpu_cache; } - shared_msrs = alloc_percpu(struct kvm_shared_msrs); - if (!shared_msrs) { - printk(KERN_ERR "kvm: failed to allocate percpu kvm_shared_msrs\n"); + user_return_msrs = alloc_percpu(struct kvm_user_return_msrs); + if (!user_return_msrs) { + printk(KERN_ERR "kvm: failed to allocate percpu kvm_user_return_msrs\n"); goto out_free_x86_emulator_cache; } @@ -7500,7 +7505,7 @@ int kvm_arch_init(void *opaque) return 0; out_free_percpu: - free_percpu(shared_msrs); + free_percpu(user_return_msrs); out_free_x86_emulator_cache: kmem_cache_destroy(x86_emulator_cache); out_free_x86_fpu_cache: @@ -7527,7 +7532,7 @@ void kvm_arch_exit(void) #endif kvm_x86_ops.hardware_enable = NULL; kvm_mmu_module_exit(); - free_percpu(shared_msrs); + free_percpu(user_return_msrs); kmem_cache_destroy(x86_fpu_cache); } @@ -9664,7 +9669,7 @@ int kvm_arch_hardware_enable(void) u64 max_tsc = 0; bool stable, backwards_tsc = false; - kvm_shared_msr_cpu_online(); + kvm_user_return_msr_cpu_online(); ret = kvm_x86_ops.hardware_enable(); if (ret != 0) return ret;