From 58f5ee5fedd981e05cb086cba4e8f923c3727a04 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Thu, 13 Oct 2022 21:12:31 +0000 Subject: [PATCH] KVM: Drop @gpa from exported gfn=>pfn cache check() and refresh() helpers Drop the @gpa param from the exported check()+refresh() helpers and limit changing the cache's GPA to the activate path. All external users just feed in gpc->gpa, i.e. this is a fancy nop. Allowing users to change the GPA at check()+refresh() is dangerous as those helpers explicitly allow concurrent calls, e.g. KVM could get into a livelock scenario. It's also unclear as to what the expected behavior should be if multiple tasks attempt to refresh with different GPAs. Signed-off-by: Sean Christopherson Signed-off-by: David Woodhouse --- arch/x86/kvm/x86.c | 6 ++---- arch/x86/kvm/xen.c | 22 +++++++++++----------- include/linux/kvm_host.h | 8 +++----- virt/kvm/pfncache.c | 17 +++++++++++------ 4 files changed, 27 insertions(+), 26 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 490df3e997fa..006b445996a9 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3035,12 +3035,10 @@ static void kvm_setup_guest_pvclock(struct kvm_vcpu *v, unsigned long flags; read_lock_irqsave(&gpc->lock, flags); - while (!kvm_gpc_check(gpc, gpc->gpa, - offset + sizeof(*guest_hv_clock))) { + while (!kvm_gpc_check(gpc, offset + sizeof(*guest_hv_clock))) { read_unlock_irqrestore(&gpc->lock, flags); - if (kvm_gpc_refresh(gpc, gpc->gpa, - offset + sizeof(*guest_hv_clock))) + if (kvm_gpc_refresh(gpc, offset + sizeof(*guest_hv_clock))) return; read_lock_irqsave(&gpc->lock, flags); diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c index f50c88b1eaab..5208e05ca9a6 100644 --- a/arch/x86/kvm/xen.c +++ b/arch/x86/kvm/xen.c @@ -272,14 +272,14 @@ static void kvm_xen_update_runstate_guest(struct kvm_vcpu *v, bool atomic) * gfn_to_pfn caches that cover the region. */ read_lock_irqsave(&gpc1->lock, flags); - while (!kvm_gpc_check(gpc1, gpc1->gpa, user_len1)) { + while (!kvm_gpc_check(gpc1, user_len1)) { read_unlock_irqrestore(&gpc1->lock, flags); /* When invoked from kvm_sched_out() we cannot sleep */ if (atomic) return; - if (kvm_gpc_refresh(gpc1, gpc1->gpa, user_len1)) + if (kvm_gpc_refresh(gpc1, user_len1)) return; read_lock_irqsave(&gpc1->lock, flags); @@ -308,7 +308,7 @@ static void kvm_xen_update_runstate_guest(struct kvm_vcpu *v, bool atomic) */ read_lock(&gpc2->lock); - if (!kvm_gpc_check(gpc2, gpc2->gpa, user_len2)) { + if (!kvm_gpc_check(gpc2, user_len2)) { read_unlock(&gpc2->lock); read_unlock_irqrestore(&gpc1->lock, flags); @@ -488,10 +488,10 @@ void kvm_xen_inject_pending_events(struct kvm_vcpu *v) * little more honest about it. */ read_lock_irqsave(&gpc->lock, flags); - while (!kvm_gpc_check(gpc, gpc->gpa, sizeof(struct vcpu_info))) { + while (!kvm_gpc_check(gpc, sizeof(struct vcpu_info))) { read_unlock_irqrestore(&gpc->lock, flags); - if (kvm_gpc_refresh(gpc, gpc->gpa, sizeof(struct vcpu_info))) + if (kvm_gpc_refresh(gpc, sizeof(struct vcpu_info))) return; read_lock_irqsave(&gpc->lock, flags); @@ -551,7 +551,7 @@ int __kvm_xen_has_interrupt(struct kvm_vcpu *v) sizeof_field(struct compat_vcpu_info, evtchn_upcall_pending)); read_lock_irqsave(&gpc->lock, flags); - while (!kvm_gpc_check(gpc, gpc->gpa, sizeof(struct vcpu_info))) { + while (!kvm_gpc_check(gpc, sizeof(struct vcpu_info))) { read_unlock_irqrestore(&gpc->lock, flags); /* @@ -565,7 +565,7 @@ int __kvm_xen_has_interrupt(struct kvm_vcpu *v) if (in_atomic() || !task_is_running(current)) return 1; - if (kvm_gpc_refresh(gpc, gpc->gpa, sizeof(struct vcpu_info))) { + if (kvm_gpc_refresh(gpc, sizeof(struct vcpu_info))) { /* * If this failed, userspace has screwed up the * vcpu_info mapping. No interrupts for you. @@ -1154,7 +1154,7 @@ static bool wait_pending_event(struct kvm_vcpu *vcpu, int nr_ports, read_lock_irqsave(&gpc->lock, flags); idx = srcu_read_lock(&kvm->srcu); - if (!kvm_gpc_check(gpc, gpc->gpa, PAGE_SIZE)) + if (!kvm_gpc_check(gpc, PAGE_SIZE)) goto out_rcu; ret = false; @@ -1576,7 +1576,7 @@ int kvm_xen_set_evtchn_fast(struct kvm_xen_evtchn *xe, struct kvm *kvm) idx = srcu_read_lock(&kvm->srcu); read_lock_irqsave(&gpc->lock, flags); - if (!kvm_gpc_check(gpc, gpc->gpa, PAGE_SIZE)) + if (!kvm_gpc_check(gpc, PAGE_SIZE)) goto out_rcu; if (IS_ENABLED(CONFIG_64BIT) && kvm->arch.xen.long_mode) { @@ -1610,7 +1610,7 @@ int kvm_xen_set_evtchn_fast(struct kvm_xen_evtchn *xe, struct kvm *kvm) gpc = &vcpu->arch.xen.vcpu_info_cache; read_lock_irqsave(&gpc->lock, flags); - if (!kvm_gpc_check(gpc, gpc->gpa, sizeof(struct vcpu_info))) { + if (!kvm_gpc_check(gpc, sizeof(struct vcpu_info))) { /* * Could not access the vcpu_info. Set the bit in-kernel * and prod the vCPU to deliver it for itself. @@ -1708,7 +1708,7 @@ static int kvm_xen_set_evtchn(struct kvm_xen_evtchn *xe, struct kvm *kvm) break; idx = srcu_read_lock(&kvm->srcu); - rc = kvm_gpc_refresh(gpc, gpc->gpa, PAGE_SIZE); + rc = kvm_gpc_refresh(gpc, PAGE_SIZE); srcu_read_unlock(&kvm->srcu, idx); } while(!rc); diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index eac76965cf44..7008846fd3dd 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1299,7 +1299,6 @@ int kvm_gpc_activate(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long len) * kvm_gpc_check - check validity of a gfn_to_pfn_cache. * * @gpc: struct gfn_to_pfn_cache object. - * @gpa: current guest physical address to map. * @len: sanity check; the range being access must fit a single page. * * @return: %true if the cache is still valid and the address matches. @@ -1312,15 +1311,14 @@ int kvm_gpc_activate(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long len) * Callers in IN_GUEST_MODE may do so without locking, although they should * still hold a read lock on kvm->scru for the memslot checks. */ -bool kvm_gpc_check(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long len); +bool kvm_gpc_check(struct gfn_to_pfn_cache *gpc, unsigned long len); /** * kvm_gpc_refresh - update a previously initialized cache. * * @gpc: struct gfn_to_pfn_cache object. - * @gpa: updated guest physical address to map. * @len: sanity check; the range being access must fit a single page. - + * * @return: 0 for success. * -EINVAL for a mapping which would cross a page boundary. * -EFAULT for an untranslatable guest physical address. @@ -1331,7 +1329,7 @@ bool kvm_gpc_check(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long len); * still lock and check the cache status, as this function does not return * with the lock still held to permit access. */ -int kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long len); +int kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, unsigned long len); /** * kvm_gpc_deactivate - deactivate and unlink a gfn_to_pfn_cache. diff --git a/virt/kvm/pfncache.c b/virt/kvm/pfncache.c index c1a772cedc4b..a805cc1544bf 100644 --- a/virt/kvm/pfncache.c +++ b/virt/kvm/pfncache.c @@ -76,18 +76,17 @@ void gfn_to_pfn_cache_invalidate_start(struct kvm *kvm, unsigned long start, } } -bool kvm_gpc_check(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long len) +bool kvm_gpc_check(struct gfn_to_pfn_cache *gpc, unsigned long len) { struct kvm_memslots *slots = kvm_memslots(gpc->kvm); if (!gpc->active) return false; - if ((gpa & ~PAGE_MASK) + len > PAGE_SIZE) + if ((gpc->gpa & ~PAGE_MASK) + len > PAGE_SIZE) return false; - if (gpc->gpa != gpa || gpc->generation != slots->generation || - kvm_is_error_hva(gpc->uhva)) + if (gpc->generation != slots->generation || kvm_is_error_hva(gpc->uhva)) return false; if (!gpc->valid) @@ -237,7 +236,8 @@ out_error: return -EFAULT; } -int kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long len) +static int __kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, gpa_t gpa, + unsigned long len) { struct kvm_memslots *slots = kvm_memslots(gpc->kvm); unsigned long page_offset = gpa & ~PAGE_MASK; @@ -331,6 +331,11 @@ out_unlock: return ret; } + +int kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, unsigned long len) +{ + return __kvm_gpc_refresh(gpc, gpc->gpa, len); +} EXPORT_SYMBOL_GPL(kvm_gpc_refresh); void kvm_gpc_init(struct gfn_to_pfn_cache *gpc, struct kvm *kvm, @@ -371,7 +376,7 @@ int kvm_gpc_activate(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long len) gpc->active = true; write_unlock_irq(&gpc->lock); } - return kvm_gpc_refresh(gpc, gpa, len); + return __kvm_gpc_refresh(gpc, gpa, len); } EXPORT_SYMBOL_GPL(kvm_gpc_activate);