From patchwork Thu Mar 3 15:41:15 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Woodhouse X-Patchwork-Id: 12767658 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C6620C433F5 for ; Thu, 3 Mar 2022 15:41:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234639AbiCCPmi (ORCPT ); Thu, 3 Mar 2022 10:42:38 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34424 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234612AbiCCPmc (ORCPT ); Thu, 3 Mar 2022 10:42:32 -0500 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 01BE61959C5 for ; Thu, 3 Mar 2022 07:41:43 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=Sender:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description; bh=U8r4iK5S+FCZaDeky71E/cb8nskAo9xMeQOAi1N+zHo=; b=RCjYK9BwgxrbCiYO65OrYi/4Lj ZC9UzWI6mR/DOcNaS5dr+ZK20tQ8vzvJpQPVI6aLq9M6LlAbGfDfa+JVB3uASLbktIoMwvdZXeqgn kYEeglzl7WfeiEm4zcUvzJ+8v4P9oOhjQGiSc8lJ6lr4KtuBIBtoq5KL8lOumz/7+bDUHFcrI5nAq 7MeVq14pfCVp99WLYURylSiWvYa2Ku8BuG+Ri6ifR9JopUAKFqMlrhbKsasO65MqLrLsWj7wNVa6f 0g8OS1nz5A6qG5lfXvHLfH3qvawhUU7cJer6IKLHUSmdbk9b8gks+NVlPBjevbX2DSZ4Pc8D/Dgxj TFBDQfew==; Received: from [2001:8b0:10b:1:85c4:81a:fb42:714d] (helo=i7.infradead.org) by desiato.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1nPna5-00Ewjv-BJ; Thu, 03 Mar 2022 15:41:29 +0000 Received: from dwoodhou by i7.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1nPna4-000qme-SN; Thu, 03 Mar 2022 15:41:28 +0000 From: David Woodhouse To: kvm@vger.kernel.org, Paolo Bonzini Cc: Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Joao Martins , Boris Ostrovsky , Metin Kaya , Paul Durrant Subject: [PATCH v3 05/17] KVM: x86/xen: Use gfn_to_pfn_cache for vcpu_info Date: Thu, 3 Mar 2022 15:41:15 +0000 Message-Id: <20220303154127.202856-6-dwmw2@infradead.org> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20220303154127.202856-1-dwmw2@infradead.org> References: <20220303154127.202856-1-dwmw2@infradead.org> MIME-Version: 1.0 Sender: David Woodhouse X-SRS-Rewrite: SMTP reverse-path rewritten from by desiato.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: David Woodhouse Currently, the fast path of kvm_xen_set_evtchn_fast() doesn't set the index bits in the target vCPU's evtchn_pending_sel, because it only has a userspace virtual address with which to do so. It just sets them in the kernel, and kvm_xen_has_interrupt() then completes the delivery to the actual vcpu_info structure when the vCPU runs. Using a gfn_to_pfn_cache allows kvm_xen_set_evtchn_fast() to do the full delivery in the common case. Clean up the fallback case too, by moving the deferred delivery out into a separate kvm_xen_inject_pending_events() function which isn't ever called in atomic contexts as __kvm_xen_has_interrupt() is. Signed-off-by: David Woodhouse --- arch/x86/include/asm/kvm_host.h | 3 +- arch/x86/kvm/x86.c | 12 +- arch/x86/kvm/xen.c | 242 +++++++++++++++++--------------- arch/x86/kvm/xen.h | 20 ++- 4 files changed, 157 insertions(+), 120 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index c98758114254..31acc17274b1 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -602,9 +602,8 @@ struct kvm_vcpu_hv { struct kvm_vcpu_xen { u64 hypercall_rip; u32 current_runstate; - bool vcpu_info_set; bool vcpu_time_info_set; - struct gfn_to_hva_cache vcpu_info_cache; + struct gfn_to_pfn_cache vcpu_info_cache; struct gfn_to_hva_cache vcpu_time_info_cache; struct gfn_to_pfn_cache runstate_cache; u64 last_steal; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 3bf7aa5e5053..fa38a00fa90d 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3136,9 +3136,9 @@ static int kvm_guest_time_update(struct kvm_vcpu *v) if (vcpu->pv_time.active) kvm_setup_guest_pvclock(v, &vcpu->pv_time, 0); - if (vcpu->xen.vcpu_info_set) - kvm_setup_pvclock_page(v, &vcpu->xen.vcpu_info_cache, - offsetof(struct compat_vcpu_info, time)); + if (vcpu->xen.vcpu_info_cache.active) + kvm_setup_guest_pvclock(v, &vcpu->xen.vcpu_info_cache, + offsetof(struct compat_vcpu_info, time)); if (vcpu->xen.vcpu_time_info_set) kvm_setup_pvclock_page(v, &vcpu->xen.vcpu_time_info_cache, 0); if (!v->vcpu_idx) @@ -10338,6 +10338,9 @@ static int vcpu_run(struct kvm_vcpu *vcpu) break; kvm_clear_request(KVM_REQ_UNBLOCK, vcpu); + if (kvm_xen_has_pending_events(vcpu)) + kvm_xen_inject_pending_events(vcpu); + if (kvm_cpu_has_pending_timer(vcpu)) kvm_inject_pending_timer_irqs(vcpu); @@ -12142,6 +12145,9 @@ static inline bool kvm_vcpu_has_events(struct kvm_vcpu *vcpu) kvm_x86_ops.nested_ops->hv_timer_pending(vcpu)) return true; + if (kvm_xen_has_pending_events(vcpu)) + return true; + return false; } diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c index de1b3be7239e..56e8a6980b65 100644 --- a/arch/x86/kvm/xen.c +++ b/arch/x86/kvm/xen.c @@ -8,6 +8,7 @@ #include "x86.h" #include "xen.h" +#include "lapic.h" #include "hyperv.h" #include @@ -246,23 +247,79 @@ void kvm_xen_update_runstate_guest(struct kvm_vcpu *v, int state) mark_page_dirty_in_slot(v->kvm, gpc->memslot, gpc->gpa >> PAGE_SHIFT); } -int __kvm_xen_has_interrupt(struct kvm_vcpu *v) +/* + * On event channel delivery, the vcpu_info may not have been accessible. + * In that case, there are bits in vcpu->arch.xen.evtchn_pending_sel which + * need to be marked into the vcpu_info (and evtchn_upcall_pending set). + * Do so now that we can sleep in the context of the vCPU to bring the + * page in, and refresh the pfn cache for it. + */ +void kvm_xen_inject_pending_events(struct kvm_vcpu *v) { unsigned long evtchn_pending_sel = READ_ONCE(v->arch.xen.evtchn_pending_sel); - bool atomic = in_atomic() || !task_is_running(current); - int err; + struct gfn_to_pfn_cache *gpc = &v->arch.xen.vcpu_info_cache; + unsigned long flags; + + if (!evtchn_pending_sel) + return; + + /* + * Yes, this is an open-coded loop. But that's just what put_user() + * does anyway. Page it in and retry the instruction. We're just a + * little more honest about it. + */ + read_lock_irqsave(&gpc->lock, flags); + while (!kvm_gfn_to_pfn_cache_check(v->kvm, gpc, gpc->gpa, + sizeof(struct vcpu_info))) { + read_unlock_irqrestore(&gpc->lock, flags); + + if (kvm_gfn_to_pfn_cache_refresh(v->kvm, gpc, gpc->gpa, + sizeof(struct vcpu_info))) + return; + + read_lock_irqsave(&gpc->lock, flags); + } + + /* Now gpc->khva is a valid kernel address for the vcpu_info */ + if (IS_ENABLED(CONFIG_64BIT) && v->kvm->arch.xen.long_mode) { + struct vcpu_info *vi = gpc->khva; + + asm volatile(LOCK_PREFIX "orq %0, %1\n" + "notq %0\n" + LOCK_PREFIX "andq %0, %2\n" + : "=r" (evtchn_pending_sel), + "+m" (vi->evtchn_pending_sel), + "+m" (v->arch.xen.evtchn_pending_sel) + : "0" (evtchn_pending_sel)); + WRITE_ONCE(vi->evtchn_upcall_pending, 1); + } else { + u32 evtchn_pending_sel32 = evtchn_pending_sel; + struct compat_vcpu_info *vi = gpc->khva; + + asm volatile(LOCK_PREFIX "orl %0, %1\n" + "notl %0\n" + LOCK_PREFIX "andl %0, %2\n" + : "=r" (evtchn_pending_sel32), + "+m" (vi->evtchn_pending_sel), + "+m" (v->arch.xen.evtchn_pending_sel) + : "0" (evtchn_pending_sel32)); + WRITE_ONCE(vi->evtchn_upcall_pending, 1); + } + read_unlock_irqrestore(&gpc->lock, flags); + + mark_page_dirty_in_slot(v->kvm, gpc->memslot, gpc->gpa >> PAGE_SHIFT); +} + +int __kvm_xen_has_interrupt(struct kvm_vcpu *v) +{ + struct gfn_to_pfn_cache *gpc = &v->arch.xen.vcpu_info_cache; + unsigned long flags; u8 rc = 0; /* * If the global upcall vector (HVMIRQ_callback_vector) is set and * the vCPU's evtchn_upcall_pending flag is set, the IRQ is pending. */ - struct gfn_to_hva_cache *ghc = &v->arch.xen.vcpu_info_cache; - struct kvm_memslots *slots = kvm_memslots(v->kvm); - bool ghc_valid = slots->generation == ghc->generation && - !kvm_is_error_hva(ghc->hva) && ghc->memslot; - - unsigned int offset = offsetof(struct vcpu_info, evtchn_upcall_pending); /* No need for compat handling here */ BUILD_BUG_ON(offsetof(struct vcpu_info, evtchn_upcall_pending) != @@ -272,101 +329,35 @@ int __kvm_xen_has_interrupt(struct kvm_vcpu *v) BUILD_BUG_ON(sizeof(rc) != sizeof_field(struct compat_vcpu_info, evtchn_upcall_pending)); - /* - * For efficiency, this mirrors the checks for using the valid - * cache in kvm_read_guest_offset_cached(), but just uses - * __get_user() instead. And falls back to the slow path. - */ - if (!evtchn_pending_sel && ghc_valid) { - /* Fast path */ - pagefault_disable(); - err = __get_user(rc, (u8 __user *)ghc->hva + offset); - pagefault_enable(); - if (!err) - return rc; - } - - /* Slow path */ + read_lock_irqsave(&gpc->lock, flags); + while (!kvm_gfn_to_pfn_cache_check(v->kvm, gpc, gpc->gpa, + sizeof(struct vcpu_info))) { + read_unlock_irqrestore(&gpc->lock, flags); - /* - * This function gets called from kvm_vcpu_block() after setting the - * task to TASK_INTERRUPTIBLE, to see if it needs to wake immediately - * from a HLT. So we really mustn't sleep. If the page ended up absent - * at that point, just return 1 in order to trigger an immediate wake, - * and we'll end up getting called again from a context where we *can* - * fault in the page and wait for it. - */ - if (atomic) - return 1; + /* + * This function gets called from kvm_vcpu_block() after setting the + * task to TASK_INTERRUPTIBLE, to see if it needs to wake immediately + * from a HLT. So we really mustn't sleep. If the page ended up absent + * at that point, just return 1 in order to trigger an immediate wake, + * and we'll end up getting called again from a context where we *can* + * fault in the page and wait for it. + */ + if (in_atomic() || !task_is_running(current)) + return 1; - if (!ghc_valid) { - err = kvm_gfn_to_hva_cache_init(v->kvm, ghc, ghc->gpa, ghc->len); - if (err || !ghc->memslot) { + if (kvm_gfn_to_pfn_cache_refresh(v->kvm, gpc, gpc->gpa, + sizeof(struct vcpu_info))) { /* * If this failed, userspace has screwed up the * vcpu_info mapping. No interrupts for you. */ return 0; } + read_lock_irqsave(&gpc->lock, flags); } - /* - * Now we have a valid (protected by srcu) userspace HVA in - * ghc->hva which points to the struct vcpu_info. If there - * are any bits in the in-kernel evtchn_pending_sel then - * we need to write those to the guest vcpu_info and set - * its evtchn_upcall_pending flag. If there aren't any bits - * to add, we only want to *check* evtchn_upcall_pending. - */ - if (evtchn_pending_sel) { - bool long_mode = v->kvm->arch.xen.long_mode; - - if (!user_access_begin((void __user *)ghc->hva, sizeof(struct vcpu_info))) - return 0; - - if (IS_ENABLED(CONFIG_64BIT) && long_mode) { - struct vcpu_info __user *vi = (void __user *)ghc->hva; - - /* Attempt to set the evtchn_pending_sel bits in the - * guest, and if that succeeds then clear the same - * bits in the in-kernel version. */ - asm volatile("1:\t" LOCK_PREFIX "orq %0, %1\n" - "\tnotq %0\n" - "\t" LOCK_PREFIX "andq %0, %2\n" - "2:\n" - _ASM_EXTABLE_UA(1b, 2b) - : "=r" (evtchn_pending_sel), - "+m" (vi->evtchn_pending_sel), - "+m" (v->arch.xen.evtchn_pending_sel) - : "0" (evtchn_pending_sel)); - } else { - struct compat_vcpu_info __user *vi = (void __user *)ghc->hva; - u32 evtchn_pending_sel32 = evtchn_pending_sel; - - /* Attempt to set the evtchn_pending_sel bits in the - * guest, and if that succeeds then clear the same - * bits in the in-kernel version. */ - asm volatile("1:\t" LOCK_PREFIX "orl %0, %1\n" - "\tnotl %0\n" - "\t" LOCK_PREFIX "andl %0, %2\n" - "2:\n" - _ASM_EXTABLE_UA(1b, 2b) - : "=r" (evtchn_pending_sel32), - "+m" (vi->evtchn_pending_sel), - "+m" (v->arch.xen.evtchn_pending_sel) - : "0" (evtchn_pending_sel32)); - } - rc = 1; - unsafe_put_user(rc, (u8 __user *)ghc->hva + offset, err); - - err: - user_access_end(); - - mark_page_dirty_in_slot(v->kvm, ghc->memslot, ghc->gpa >> PAGE_SHIFT); - } else { - __get_user(rc, (u8 __user *)ghc->hva + offset); - } - + rc = ((struct vcpu_info *)gpc->khva)->evtchn_upcall_pending; + read_unlock_irqrestore(&gpc->lock, flags); return rc; } @@ -456,25 +447,18 @@ int kvm_xen_vcpu_set_attr(struct kvm_vcpu *vcpu, struct kvm_xen_vcpu_attr *data) offsetof(struct compat_vcpu_info, time)); if (data->u.gpa == GPA_INVALID) { - vcpu->arch.xen.vcpu_info_set = false; + kvm_gfn_to_pfn_cache_destroy(vcpu->kvm, &vcpu->arch.xen.vcpu_info_cache); r = 0; break; } - /* It must fit within a single page */ - if ((data->u.gpa & ~PAGE_MASK) + sizeof(struct vcpu_info) > PAGE_SIZE) { - r = -EINVAL; - break; - } - - r = kvm_gfn_to_hva_cache_init(vcpu->kvm, + r = kvm_gfn_to_pfn_cache_init(vcpu->kvm, &vcpu->arch.xen.vcpu_info_cache, - data->u.gpa, + NULL, KVM_HOST_USES_PFN, data->u.gpa, sizeof(struct vcpu_info)); - if (!r) { - vcpu->arch.xen.vcpu_info_set = true; + if (!r) kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu); - } + break; case KVM_XEN_VCPU_ATTR_TYPE_VCPU_TIME_INFO: @@ -630,7 +614,7 @@ int kvm_xen_vcpu_get_attr(struct kvm_vcpu *vcpu, struct kvm_xen_vcpu_attr *data) switch (data->type) { case KVM_XEN_VCPU_ATTR_TYPE_VCPU_INFO: - if (vcpu->arch.xen.vcpu_info_set) + if (vcpu->arch.xen.vcpu_info_cache.active) data->u.gpa = vcpu->arch.xen.vcpu_info_cache.gpa; else data->u.gpa = GPA_INVALID; @@ -903,16 +887,17 @@ int kvm_xen_set_evtchn_fast(struct kvm_kernel_irq_routing_entry *e, if (!vcpu) return -1; - if (!vcpu->arch.xen.vcpu_info_set) + if (!vcpu->arch.xen.vcpu_info_cache.active) return -1; if (e->xen_evtchn.port >= max_evtchn_port(kvm)) return -1; rc = -EWOULDBLOCK; - read_lock_irqsave(&gpc->lock, flags); idx = srcu_read_lock(&kvm->srcu); + + read_lock_irqsave(&gpc->lock, flags); if (!kvm_gfn_to_pfn_cache_check(kvm, gpc, gpc->gpa, PAGE_SIZE)) goto out_rcu; @@ -940,17 +925,44 @@ int kvm_xen_set_evtchn_fast(struct kvm_kernel_irq_routing_entry *e, } else if (test_bit(e->xen_evtchn.port, mask_bits)) { rc = -1; /* Masked */ } else { - rc = 1; /* Delivered. But was the vCPU waking already? */ - if (!test_and_set_bit(port_word_bit, &vcpu->arch.xen.evtchn_pending_sel)) - kick_vcpu = true; + rc = 1; /* Delivered to the bitmap in shared_info. */ + /* Now switch to the vCPU's vcpu_info to set the index and pending_sel */ + read_unlock_irqrestore(&gpc->lock, flags); + gpc = &vcpu->arch.xen.vcpu_info_cache; + + read_lock_irqsave(&gpc->lock, flags); + if (!kvm_gfn_to_pfn_cache_check(kvm, gpc, gpc->gpa, sizeof(struct vcpu_info))) { + /* + * Could not access the vcpu_info. Set the bit in-kernel + * and prod the vCPU to deliver it for itself. + */ + if (!test_and_set_bit(port_word_bit, &vcpu->arch.xen.evtchn_pending_sel)) + kick_vcpu = true; + goto out_rcu; + } + + if (IS_ENABLED(CONFIG_64BIT) && kvm->arch.xen.long_mode) { + struct vcpu_info *vcpu_info = gpc->khva; + if (!test_and_set_bit(port_word_bit, &vcpu_info->evtchn_pending_sel)) { + WRITE_ONCE(vcpu_info->evtchn_upcall_pending, 1); + kick_vcpu = true; + } + } else { + struct compat_vcpu_info *vcpu_info = gpc->khva; + if (!test_and_set_bit(port_word_bit, + (unsigned long *)&vcpu_info->evtchn_pending_sel)) { + WRITE_ONCE(vcpu_info->evtchn_upcall_pending, 1); + kick_vcpu = true; + } + } } out_rcu: - srcu_read_unlock(&kvm->srcu, idx); read_unlock_irqrestore(&gpc->lock, flags); + srcu_read_unlock(&kvm->srcu, idx); if (kick_vcpu) { - kvm_make_request(KVM_REQ_EVENT, vcpu); + kvm_make_request(KVM_REQ_UNBLOCK, vcpu); kvm_vcpu_kick(vcpu); } @@ -1052,4 +1064,6 @@ void kvm_xen_destroy_vcpu(struct kvm_vcpu *vcpu) { kvm_gfn_to_pfn_cache_destroy(vcpu->kvm, &vcpu->arch.xen.runstate_cache); + kvm_gfn_to_pfn_cache_destroy(vcpu->kvm, + &vcpu->arch.xen.vcpu_info_cache); } diff --git a/arch/x86/kvm/xen.h b/arch/x86/kvm/xen.h index 54b2bf4c3001..7dd0590f93e1 100644 --- a/arch/x86/kvm/xen.h +++ b/arch/x86/kvm/xen.h @@ -15,6 +15,7 @@ extern struct static_key_false_deferred kvm_xen_enabled; int __kvm_xen_has_interrupt(struct kvm_vcpu *vcpu); +void kvm_xen_inject_pending_events(struct kvm_vcpu *vcpu); int kvm_xen_vcpu_set_attr(struct kvm_vcpu *vcpu, struct kvm_xen_vcpu_attr *data); int kvm_xen_vcpu_get_attr(struct kvm_vcpu *vcpu, struct kvm_xen_vcpu_attr *data); int kvm_xen_hvm_set_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data); @@ -46,11 +47,19 @@ static inline bool kvm_xen_hypercall_enabled(struct kvm *kvm) static inline int kvm_xen_has_interrupt(struct kvm_vcpu *vcpu) { if (static_branch_unlikely(&kvm_xen_enabled.key) && - vcpu->arch.xen.vcpu_info_set && vcpu->kvm->arch.xen.upcall_vector) + vcpu->arch.xen.vcpu_info_cache.active && + vcpu->kvm->arch.xen.upcall_vector) return __kvm_xen_has_interrupt(vcpu); return 0; } + +static inline bool kvm_xen_has_pending_events(struct kvm_vcpu *vcpu) +{ + return static_branch_unlikely(&kvm_xen_enabled.key) && + vcpu->arch.xen.evtchn_pending_sel; +} + #else static inline int kvm_xen_write_hypercall_page(struct kvm_vcpu *vcpu, u64 data) { @@ -83,6 +92,15 @@ static inline int kvm_xen_has_interrupt(struct kvm_vcpu *vcpu) { return 0; } + +static inline void kvm_xen_inject_pending_events(struct kvm_vcpu *vcpu) +{ +} + +static inline bool kvm_xen_has_pending_events(struct kvm_vcpu *vcpu) +{ + return false; +} #endif int kvm_xen_hypercall(struct kvm_vcpu *vcpu);