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authorPaolo Bonzini <pbonzini@redhat.com>2022-07-29 09:46:01 -0400
committerPaolo Bonzini <pbonzini@redhat.com>2022-08-01 03:21:00 -0400
commit63f4b210414b65aa3103c54369cacbd0b1bdf02f (patch)
tree2dc7b490d3a89306669c70256a41764ca52ab3b3 /virt/kvm
parent2e2e91158febfeb73b5d4f249440218304f34101 (diff)
parent7edc3a68038ab151a8791ddb6217755a5e4a5809 (diff)
Merge remote-tracking branch 'kvm/next' into kvm-next-5.20
KVM/s390, KVM/x86 and common infrastructure changes for 5.20 x86: * Permit guests to ignore single-bit ECC errors * Fix races in gfn->pfn cache refresh; do not pin pages tracked by the cache * Intel IPI virtualization * Allow getting/setting pending triple fault with KVM_GET/SET_VCPU_EVENTS * PEBS virtualization * Simplify PMU emulation by just using PERF_TYPE_RAW events * More accurate event reinjection on SVM (avoid retrying instructions) * Allow getting/setting the state of the speaker port data bit * Refuse starting the kvm-intel module if VM-Entry/VM-Exit controls are inconsistent * "Notify" VM exit (detect microarchitectural hangs) for Intel * Cleanups for MCE MSR emulation s390: * add an interface to provide a hypervisor dump for secure guests * improve selftests to use TAP interface * enable interpretive execution of zPCI instructions (for PCI passthrough) * First part of deferred teardown * CPU Topology * PV attestation * Minor fixes Generic: * new selftests API using struct kvm_vcpu instead of a (vm, id) tuple x86: * Use try_cmpxchg64 instead of cmpxchg64 * Bugfixes * Ignore benign host accesses to PMU MSRs when PMU is disabled * Allow disabling KVM's "MONITOR/MWAIT are NOPs!" behavior * x86/MMU: Allow NX huge pages to be disabled on a per-vm basis * Port eager page splitting to shadow MMU as well * Enable CMCI capability by default and handle injected UCNA errors * Expose pid of vcpu threads in debugfs * x2AVIC support for AMD * cleanup PIO emulation * Fixes for LLDT/LTR emulation * Don't require refcounted "struct page" to create huge SPTEs x86 cleanups: * Use separate namespaces for guest PTEs and shadow PTEs bitmasks * PIO emulation * Reorganize rmap API, mostly around rmap destruction * Do not workaround very old KVM bugs for L0 that runs with nesting enabled * new selftests API for CPUID
Diffstat (limited to 'virt/kvm')
-rw-r--r--virt/kvm/kvm_main.c219
-rw-r--r--virt/kvm/pfncache.c231
2 files changed, 312 insertions, 138 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index e3a6f7647474..32896c845ffe 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -168,7 +168,7 @@ __weak void kvm_arch_guest_memory_reclaimed(struct kvm *kvm)
{
}
-bool kvm_is_zone_device_pfn(kvm_pfn_t pfn)
+bool kvm_is_zone_device_page(struct page *page)
{
/*
* The metadata used by is_zone_device_page() to determine whether or
@@ -176,25 +176,42 @@ bool kvm_is_zone_device_pfn(kvm_pfn_t pfn)
* the device has been pinned, e.g. by get_user_pages(). WARN if the
* page_count() is zero to help detect bad usage of this helper.
*/
- if (!pfn_valid(pfn) || WARN_ON_ONCE(!page_count(pfn_to_page(pfn))))
+ if (WARN_ON_ONCE(!page_count(page)))
return false;
- return is_zone_device_page(pfn_to_page(pfn));
+ return is_zone_device_page(page);
}
-bool kvm_is_reserved_pfn(kvm_pfn_t pfn)
+/*
+ * Returns a 'struct page' if the pfn is "valid" and backed by a refcounted
+ * page, NULL otherwise. Note, the list of refcounted PG_reserved page types
+ * is likely incomplete, it has been compiled purely through people wanting to
+ * back guest with a certain type of memory and encountering issues.
+ */
+struct page *kvm_pfn_to_refcounted_page(kvm_pfn_t pfn)
{
+ struct page *page;
+
+ if (!pfn_valid(pfn))
+ return NULL;
+
+ page = pfn_to_page(pfn);
+ if (!PageReserved(page))
+ return page;
+
+ /* The ZERO_PAGE(s) is marked PG_reserved, but is refcounted. */
+ if (is_zero_pfn(pfn))
+ return page;
+
/*
* ZONE_DEVICE pages currently set PG_reserved, but from a refcounting
* perspective they are "normal" pages, albeit with slightly different
* usage rules.
*/
- if (pfn_valid(pfn))
- return PageReserved(pfn_to_page(pfn)) &&
- !is_zero_pfn(pfn) &&
- !kvm_is_zone_device_pfn(pfn);
+ if (kvm_is_zone_device_page(page))
+ return page;
- return true;
+ return NULL;
}
/*
@@ -239,7 +256,7 @@ static bool kvm_request_needs_ipi(struct kvm_vcpu *vcpu, unsigned req)
return mode == IN_GUEST_MODE;
}
-static void ack_flush(void *_completed)
+static void ack_kick(void *_completed)
{
}
@@ -248,7 +265,7 @@ static inline bool kvm_kick_many_cpus(struct cpumask *cpus, bool wait)
if (cpumask_empty(cpus))
return false;
- smp_call_function_many(cpus, ack_flush, NULL, wait);
+ smp_call_function_many(cpus, ack_kick, NULL, wait);
return true;
}
@@ -379,16 +396,31 @@ static inline void *mmu_memory_cache_alloc_obj(struct kvm_mmu_memory_cache *mc,
return (void *)__get_free_page(gfp_flags);
}
-int kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int min)
+int __kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int capacity, int min)
{
+ gfp_t gfp = mc->gfp_custom ? mc->gfp_custom : GFP_KERNEL_ACCOUNT;
void *obj;
if (mc->nobjs >= min)
return 0;
- while (mc->nobjs < ARRAY_SIZE(mc->objects)) {
- obj = mmu_memory_cache_alloc_obj(mc, (mc->gfp_custom) ?
- mc->gfp_custom :
- GFP_KERNEL_ACCOUNT);
+
+ if (unlikely(!mc->objects)) {
+ if (WARN_ON_ONCE(!capacity))
+ return -EIO;
+
+ mc->objects = kvmalloc_array(sizeof(void *), capacity, gfp);
+ if (!mc->objects)
+ return -ENOMEM;
+
+ mc->capacity = capacity;
+ }
+
+ /* It is illegal to request a different capacity across topups. */
+ if (WARN_ON_ONCE(mc->capacity != capacity))
+ return -EIO;
+
+ while (mc->nobjs < mc->capacity) {
+ obj = mmu_memory_cache_alloc_obj(mc, gfp);
if (!obj)
return mc->nobjs >= min ? 0 : -ENOMEM;
mc->objects[mc->nobjs++] = obj;
@@ -396,6 +428,11 @@ int kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int min)
return 0;
}
+int kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int min)
+{
+ return __kvm_mmu_topup_memory_cache(mc, KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE, min);
+}
+
int kvm_mmu_memory_cache_nr_free_objects(struct kvm_mmu_memory_cache *mc)
{
return mc->nobjs;
@@ -409,6 +446,11 @@ void kvm_mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc)
else
free_page((unsigned long)mc->objects[--mc->nobjs]);
}
+
+ kvfree(mc->objects);
+
+ mc->objects = NULL;
+ mc->capacity = 0;
}
void *kvm_mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc)
@@ -726,6 +768,15 @@ static int kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn,
kvm->mn_active_invalidate_count++;
spin_unlock(&kvm->mn_invalidate_lock);
+ /*
+ * Invalidate pfn caches _before_ invalidating the secondary MMUs, i.e.
+ * before acquiring mmu_lock, to avoid holding mmu_lock while acquiring
+ * each cache's lock. There are relatively few caches in existence at
+ * any given time, and the caches themselves can check for hva overlap,
+ * i.e. don't need to rely on memslot overlap checks for performance.
+ * Because this runs without holding mmu_lock, the pfn caches must use
+ * mn_active_invalidate_count (see above) instead of mmu_notifier_count.
+ */
gfn_to_pfn_cache_invalidate_start(kvm, range->start, range->end,
hva_range.may_block);
@@ -2494,9 +2545,12 @@ static bool vma_is_valid(struct vm_area_struct *vma, bool write_fault)
static int kvm_try_get_pfn(kvm_pfn_t pfn)
{
- if (kvm_is_reserved_pfn(pfn))
+ struct page *page = kvm_pfn_to_refcounted_page(pfn);
+
+ if (!page)
return 1;
- return get_page_unless_zero(pfn_to_page(pfn));
+
+ return get_page_unless_zero(page);
}
static int hva_to_pfn_remapped(struct vm_area_struct *vma,
@@ -2582,7 +2636,7 @@ kvm_pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async,
bool write_fault, bool *writable)
{
struct vm_area_struct *vma;
- kvm_pfn_t pfn = 0;
+ kvm_pfn_t pfn;
int npages, r;
/* we can do it either atomically or asynchronously, not both */
@@ -2713,34 +2767,32 @@ int gfn_to_page_many_atomic(struct kvm_memory_slot *slot, gfn_t gfn,
}
EXPORT_SYMBOL_GPL(gfn_to_page_many_atomic);
-static struct page *kvm_pfn_to_page(kvm_pfn_t pfn)
-{
- if (is_error_noslot_pfn(pfn))
- return KVM_ERR_PTR_BAD_PAGE;
-
- if (kvm_is_reserved_pfn(pfn)) {
- WARN_ON(1);
- return KVM_ERR_PTR_BAD_PAGE;
- }
-
- return pfn_to_page(pfn);
-}
-
+/*
+ * Do not use this helper unless you are absolutely certain the gfn _must_ be
+ * backed by 'struct page'. A valid example is if the backing memslot is
+ * controlled by KVM. Note, if the returned page is valid, it's refcount has
+ * been elevated by gfn_to_pfn().
+ */
struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn)
{
+ struct page *page;
kvm_pfn_t pfn;
pfn = gfn_to_pfn(kvm, gfn);
- return kvm_pfn_to_page(pfn);
+ if (is_error_noslot_pfn(pfn))
+ return KVM_ERR_PTR_BAD_PAGE;
+
+ page = kvm_pfn_to_refcounted_page(pfn);
+ if (!page)
+ return KVM_ERR_PTR_BAD_PAGE;
+
+ return page;
}
EXPORT_SYMBOL_GPL(gfn_to_page);
void kvm_release_pfn(kvm_pfn_t pfn, bool dirty)
{
- if (pfn == 0)
- return;
-
if (dirty)
kvm_release_pfn_dirty(pfn);
else
@@ -2806,28 +2858,48 @@ void kvm_vcpu_unmap(struct kvm_vcpu *vcpu, struct kvm_host_map *map, bool dirty)
}
EXPORT_SYMBOL_GPL(kvm_vcpu_unmap);
-struct page *kvm_vcpu_gfn_to_page(struct kvm_vcpu *vcpu, gfn_t gfn)
+static bool kvm_is_ad_tracked_page(struct page *page)
{
- kvm_pfn_t pfn;
+ /*
+ * Per page-flags.h, pages tagged PG_reserved "should in general not be
+ * touched (e.g. set dirty) except by its owner".
+ */
+ return !PageReserved(page);
+}
- pfn = kvm_vcpu_gfn_to_pfn(vcpu, gfn);
+static void kvm_set_page_dirty(struct page *page)
+{
+ if (kvm_is_ad_tracked_page(page))
+ SetPageDirty(page);
+}
- return kvm_pfn_to_page(pfn);
+static void kvm_set_page_accessed(struct page *page)
+{
+ if (kvm_is_ad_tracked_page(page))
+ mark_page_accessed(page);
}
-EXPORT_SYMBOL_GPL(kvm_vcpu_gfn_to_page);
void kvm_release_page_clean(struct page *page)
{
WARN_ON(is_error_page(page));
- kvm_release_pfn_clean(page_to_pfn(page));
+ kvm_set_page_accessed(page);
+ put_page(page);
}
EXPORT_SYMBOL_GPL(kvm_release_page_clean);
void kvm_release_pfn_clean(kvm_pfn_t pfn)
{
- if (!is_error_noslot_pfn(pfn) && !kvm_is_reserved_pfn(pfn))
- put_page(pfn_to_page(pfn));
+ struct page *page;
+
+ if (is_error_noslot_pfn(pfn))
+ return;
+
+ page = kvm_pfn_to_refcounted_page(pfn);
+ if (!page)
+ return;
+
+ kvm_release_page_clean(page);
}
EXPORT_SYMBOL_GPL(kvm_release_pfn_clean);
@@ -2835,28 +2907,48 @@ void kvm_release_page_dirty(struct page *page)
{
WARN_ON(is_error_page(page));
- kvm_release_pfn_dirty(page_to_pfn(page));
+ kvm_set_page_dirty(page);
+ kvm_release_page_clean(page);
}
EXPORT_SYMBOL_GPL(kvm_release_page_dirty);
void kvm_release_pfn_dirty(kvm_pfn_t pfn)
{
- kvm_set_pfn_dirty(pfn);
- kvm_release_pfn_clean(pfn);
+ struct page *page;
+
+ if (is_error_noslot_pfn(pfn))
+ return;
+
+ page = kvm_pfn_to_refcounted_page(pfn);
+ if (!page)
+ return;
+
+ kvm_release_page_dirty(page);
}
EXPORT_SYMBOL_GPL(kvm_release_pfn_dirty);
+/*
+ * Note, checking for an error/noslot pfn is the caller's responsibility when
+ * directly marking a page dirty/accessed. Unlike the "release" helpers, the
+ * "set" helpers are not to be used when the pfn might point at garbage.
+ */
void kvm_set_pfn_dirty(kvm_pfn_t pfn)
{
- if (!kvm_is_reserved_pfn(pfn) && !kvm_is_zone_device_pfn(pfn))
- SetPageDirty(pfn_to_page(pfn));
+ if (WARN_ON(is_error_noslot_pfn(pfn)))
+ return;
+
+ if (pfn_valid(pfn))
+ kvm_set_page_dirty(pfn_to_page(pfn));
}
EXPORT_SYMBOL_GPL(kvm_set_pfn_dirty);
void kvm_set_pfn_accessed(kvm_pfn_t pfn)
{
- if (!kvm_is_reserved_pfn(pfn) && !kvm_is_zone_device_pfn(pfn))
- mark_page_accessed(pfn_to_page(pfn));
+ if (WARN_ON(is_error_noslot_pfn(pfn)))
+ return;
+
+ if (pfn_valid(pfn))
+ kvm_set_page_accessed(pfn_to_page(pfn));
}
EXPORT_SYMBOL_GPL(kvm_set_pfn_accessed);
@@ -3730,9 +3822,18 @@ static int create_vcpu_fd(struct kvm_vcpu *vcpu)
return anon_inode_getfd(name, &kvm_vcpu_fops, vcpu, O_RDWR | O_CLOEXEC);
}
+#ifdef __KVM_HAVE_ARCH_VCPU_DEBUGFS
+static int vcpu_get_pid(void *data, u64 *val)
+{
+ struct kvm_vcpu *vcpu = (struct kvm_vcpu *) data;
+ *val = pid_nr(rcu_access_pointer(vcpu->pid));
+ return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(vcpu_get_pid_fops, vcpu_get_pid, NULL, "%llu\n");
+
static void kvm_create_vcpu_debugfs(struct kvm_vcpu *vcpu)
{
-#ifdef __KVM_HAVE_ARCH_VCPU_DEBUGFS
struct dentry *debugfs_dentry;
char dir_name[ITOA_MAX_LEN * 2];
@@ -3742,10 +3843,12 @@ static void kvm_create_vcpu_debugfs(struct kvm_vcpu *vcpu)
snprintf(dir_name, sizeof(dir_name), "vcpu%d", vcpu->vcpu_id);
debugfs_dentry = debugfs_create_dir(dir_name,
vcpu->kvm->debugfs_dentry);
+ debugfs_create_file("pid", 0444, debugfs_dentry, vcpu,
+ &vcpu_get_pid_fops);
kvm_arch_create_vcpu_debugfs(vcpu, debugfs_dentry);
-#endif
}
+#endif
/*
* Creates some virtual cpus. Good luck creating more than one.
@@ -3765,13 +3868,15 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
return -EINVAL;
}
+ r = kvm_arch_vcpu_precreate(kvm, id);
+ if (r) {
+ mutex_unlock(&kvm->lock);
+ return r;
+ }
+
kvm->created_vcpus++;
mutex_unlock(&kvm->lock);
- r = kvm_arch_vcpu_precreate(kvm, id);
- if (r)
- goto vcpu_decrement;
-
vcpu = kmem_cache_zalloc(kvm_vcpu_cache, GFP_KERNEL_ACCOUNT);
if (!vcpu) {
r = -ENOMEM;
diff --git a/virt/kvm/pfncache.c b/virt/kvm/pfncache.c
index dd84676615f1..ab519f72f2cd 100644
--- a/virt/kvm/pfncache.c
+++ b/virt/kvm/pfncache.c
@@ -95,48 +95,143 @@ bool kvm_gfn_to_pfn_cache_check(struct kvm *kvm, struct gfn_to_pfn_cache *gpc,
}
EXPORT_SYMBOL_GPL(kvm_gfn_to_pfn_cache_check);
-static void __release_gpc(struct kvm *kvm, kvm_pfn_t pfn, void *khva, gpa_t gpa)
+static void gpc_unmap_khva(struct kvm *kvm, kvm_pfn_t pfn, void *khva)
{
- /* Unmap the old page if it was mapped before, and release it */
- if (!is_error_noslot_pfn(pfn)) {
- if (khva) {
- if (pfn_valid(pfn))
- kunmap(pfn_to_page(pfn));
+ /* Unmap the old pfn/page if it was mapped before. */
+ if (!is_error_noslot_pfn(pfn) && khva) {
+ if (pfn_valid(pfn))
+ kunmap(pfn_to_page(pfn));
#ifdef CONFIG_HAS_IOMEM
- else
- memunmap(khva);
+ else
+ memunmap(khva);
#endif
- }
-
- kvm_release_pfn(pfn, false);
}
}
-static kvm_pfn_t hva_to_pfn_retry(struct kvm *kvm, unsigned long uhva)
+static inline bool mmu_notifier_retry_cache(struct kvm *kvm, unsigned long mmu_seq)
{
+ /*
+ * mn_active_invalidate_count acts for all intents and purposes
+ * like mmu_notifier_count here; but the latter cannot be used
+ * here because the invalidation of caches in the mmu_notifier
+ * event occurs _before_ mmu_notifier_count is elevated.
+ *
+ * Note, it does not matter that mn_active_invalidate_count
+ * is not protected by gpc->lock. It is guaranteed to
+ * be elevated before the mmu_notifier acquires gpc->lock, and
+ * isn't dropped until after mmu_notifier_seq is updated.
+ */
+ if (kvm->mn_active_invalidate_count)
+ return true;
+
+ /*
+ * Ensure mn_active_invalidate_count is read before
+ * mmu_notifier_seq. This pairs with the smp_wmb() in
+ * mmu_notifier_invalidate_range_end() to guarantee either the
+ * old (non-zero) value of mn_active_invalidate_count or the
+ * new (incremented) value of mmu_notifier_seq is observed.
+ */
+ smp_rmb();
+ return kvm->mmu_notifier_seq != mmu_seq;
+}
+
+static kvm_pfn_t hva_to_pfn_retry(struct kvm *kvm, struct gfn_to_pfn_cache *gpc)
+{
+ /* Note, the new page offset may be different than the old! */
+ void *old_khva = gpc->khva - offset_in_page(gpc->khva);
+ kvm_pfn_t new_pfn = KVM_PFN_ERR_FAULT;
+ void *new_khva = NULL;
unsigned long mmu_seq;
- kvm_pfn_t new_pfn;
- int retry;
+
+ lockdep_assert_held(&gpc->refresh_lock);
+
+ lockdep_assert_held_write(&gpc->lock);
+
+ /*
+ * Invalidate the cache prior to dropping gpc->lock, the gpa=>uhva
+ * assets have already been updated and so a concurrent check() from a
+ * different task may not fail the gpa/uhva/generation checks.
+ */
+ gpc->valid = false;
do {
mmu_seq = kvm->mmu_notifier_seq;
smp_rmb();
+ write_unlock_irq(&gpc->lock);
+
+ /*
+ * If the previous iteration "failed" due to an mmu_notifier
+ * event, release the pfn and unmap the kernel virtual address
+ * from the previous attempt. Unmapping might sleep, so this
+ * needs to be done after dropping the lock. Opportunistically
+ * check for resched while the lock isn't held.
+ */
+ if (new_pfn != KVM_PFN_ERR_FAULT) {
+ /*
+ * Keep the mapping if the previous iteration reused
+ * the existing mapping and didn't create a new one.
+ */
+ if (new_khva != old_khva)
+ gpc_unmap_khva(kvm, new_pfn, new_khva);
+
+ kvm_release_pfn_clean(new_pfn);
+
+ cond_resched();
+ }
+
/* We always request a writeable mapping */
- new_pfn = hva_to_pfn(uhva, false, NULL, true, NULL);
+ new_pfn = hva_to_pfn(gpc->uhva, false, NULL, true, NULL);
if (is_error_noslot_pfn(new_pfn))
- break;
+ goto out_error;
+
+ /*
+ * Obtain a new kernel mapping if KVM itself will access the
+ * pfn. Note, kmap() and memremap() can both sleep, so this
+ * too must be done outside of gpc->lock!
+ */
+ if (gpc->usage & KVM_HOST_USES_PFN) {
+ if (new_pfn == gpc->pfn) {
+ new_khva = old_khva;
+ } else if (pfn_valid(new_pfn)) {
+ new_khva = kmap(pfn_to_page(new_pfn));
+#ifdef CONFIG_HAS_IOMEM
+ } else {
+ new_khva = memremap(pfn_to_hpa(new_pfn), PAGE_SIZE, MEMREMAP_WB);
+#endif
+ }
+ if (!new_khva) {
+ kvm_release_pfn_clean(new_pfn);
+ goto out_error;
+ }
+ }
+
+ write_lock_irq(&gpc->lock);
+
+ /*
+ * Other tasks must wait for _this_ refresh to complete before
+ * attempting to refresh.
+ */
+ WARN_ON_ONCE(gpc->valid);
+ } while (mmu_notifier_retry_cache(kvm, mmu_seq));
+
+ gpc->valid = true;
+ gpc->pfn = new_pfn;
+ gpc->khva = new_khva + (gpc->gpa & ~PAGE_MASK);
- KVM_MMU_READ_LOCK(kvm);
- retry = mmu_notifier_retry_hva(kvm, mmu_seq, uhva);
- KVM_MMU_READ_UNLOCK(kvm);
- if (!retry)
- break;
+ /*
+ * Put the reference to the _new_ pfn. The pfn is now tracked by the
+ * cache and can be safely migrated, swapped, etc... as the cache will
+ * invalidate any mappings in response to relevant mmu_notifier events.
+ */
+ kvm_release_pfn_clean(new_pfn);
- cond_resched();
- } while (1);
+ return 0;
- return new_pfn;
+out_error:
+ write_lock_irq(&gpc->lock);
+
+ return -EFAULT;
}
int kvm_gfn_to_pfn_cache_refresh(struct kvm *kvm, struct gfn_to_pfn_cache *gpc,
@@ -146,9 +241,7 @@ int kvm_gfn_to_pfn_cache_refresh(struct kvm *kvm, struct gfn_to_pfn_cache *gpc,
unsigned long page_offset = gpa & ~PAGE_MASK;
kvm_pfn_t old_pfn, new_pfn;
unsigned long old_uhva;
- gpa_t old_gpa;
void *old_khva;
- bool old_valid;
int ret = 0;
/*
@@ -158,13 +251,18 @@ int kvm_gfn_to_pfn_cache_refresh(struct kvm *kvm, struct gfn_to_pfn_cache *gpc,
if (page_offset + len > PAGE_SIZE)
return -EINVAL;
+ /*
+ * If another task is refreshing the cache, wait for it to complete.
+ * There is no guarantee that concurrent refreshes will see the same
+ * gpa, memslots generation, etc..., so they must be fully serialized.
+ */
+ mutex_lock(&gpc->refresh_lock);
+
write_lock_irq(&gpc->lock);
- old_gpa = gpc->gpa;
old_pfn = gpc->pfn;
old_khva = gpc->khva - offset_in_page(gpc->khva);
old_uhva = gpc->uhva;
- old_valid = gpc->valid;
/* If the userspace HVA is invalid, refresh that first */
if (gpc->gpa != gpa || gpc->generation != slots->generation ||
@@ -177,64 +275,17 @@ int kvm_gfn_to_pfn_cache_refresh(struct kvm *kvm, struct gfn_to_pfn_cache *gpc,
gpc->uhva = gfn_to_hva_memslot(gpc->memslot, gfn);
if (kvm_is_error_hva(gpc->uhva)) {
- gpc->pfn = KVM_PFN_ERR_FAULT;
ret = -EFAULT;
goto out;
}
-
- gpc->uhva += page_offset;
}
/*
* If the userspace HVA changed or the PFN was already invalid,
* drop the lock and do the HVA to PFN lookup again.
*/
- if (!old_valid || old_uhva != gpc->uhva) {
- unsigned long uhva = gpc->uhva;
- void *new_khva = NULL;
-
- /* Placeholders for "hva is valid but not yet mapped" */
- gpc->pfn = KVM_PFN_ERR_FAULT;
- gpc->khva = NULL;
- gpc->valid = true;
-
- write_unlock_irq(&gpc->lock);
-
- new_pfn = hva_to_pfn_retry(kvm, uhva);
- if (is_error_noslot_pfn(new_pfn)) {
- ret = -EFAULT;
- goto map_done;
- }
-
- if (gpc->usage & KVM_HOST_USES_PFN) {
- if (new_pfn == old_pfn) {
- new_khva = old_khva;
- old_pfn = KVM_PFN_ERR_FAULT;
- old_khva = NULL;
- } else if (pfn_valid(new_pfn)) {
- new_khva = kmap(pfn_to_page(new_pfn));
-#ifdef CONFIG_HAS_IOMEM
- } else {
- new_khva = memremap(pfn_to_hpa(new_pfn), PAGE_SIZE, MEMREMAP_WB);
-#endif
- }
- if (new_khva)
- new_khva += page_offset;
- else
- ret = -EFAULT;
- }
-
- map_done:
- write_lock_irq(&gpc->lock);
- if (ret) {
- gpc->valid = false;
- gpc->pfn = KVM_PFN_ERR_FAULT;
- gpc->khva = NULL;
- } else {
- /* At this point, gpc->valid may already have been cleared */
- gpc->pfn = new_pfn;
- gpc->khva = new_khva;
- }
+ if (!gpc->valid || old_uhva != gpc->uhva) {
+ ret = hva_to_pfn_retry(kvm, gpc);
} else {
/* If the HVA→PFN mapping was already valid, don't unmap it. */
old_pfn = KVM_PFN_ERR_FAULT;
@@ -242,9 +293,26 @@ int kvm_gfn_to_pfn_cache_refresh(struct kvm *kvm, struct gfn_to_pfn_cache *gpc,
}
out:
+ /*
+ * Invalidate the cache and purge the pfn/khva if the refresh failed.
+ * Some/all of the uhva, gpa, and memslot generation info may still be
+ * valid, leave it as is.
+ */
+ if (ret) {
+ gpc->valid = false;
+ gpc->pfn = KVM_PFN_ERR_FAULT;
+ gpc->khva = NULL;
+ }
+
+ /* Snapshot the new pfn before dropping the lock! */
+ new_pfn = gpc->pfn;
+
write_unlock_irq(&gpc->lock);
- __release_gpc(kvm, old_pfn, old_khva, old_gpa);
+ mutex_unlock(&gpc->refresh_lock);
+
+ if (old_pfn != new_pfn)
+ gpc_unmap_khva(kvm, old_pfn, old_khva);
return ret;
}
@@ -254,14 +322,13 @@ void kvm_gfn_to_pfn_cache_unmap(struct kvm *kvm, struct gfn_to_pfn_cache *gpc)
{
void *old_khva;
kvm_pfn_t old_pfn;
- gpa_t old_gpa;
+ mutex_lock(&gpc->refresh_lock);
write_lock_irq(&gpc->lock);
gpc->valid = false;
old_khva = gpc->khva - offset_in_page(gpc->khva);
- old_gpa = gpc->gpa;
old_pfn = gpc->pfn;
/*
@@ -272,8 +339,9 @@ void kvm_gfn_to_pfn_cache_unmap(struct kvm *kvm, struct gfn_to_pfn_cache *gpc)
gpc->pfn = KVM_PFN_ERR_FAULT;
write_unlock_irq(&gpc->lock);
+ mutex_unlock(&gpc->refresh_lock);
- __release_gpc(kvm, old_pfn, old_khva, old_gpa);
+ gpc_unmap_khva(kvm, old_pfn, old_khva);
}
EXPORT_SYMBOL_GPL(kvm_gfn_to_pfn_cache_unmap);
@@ -286,6 +354,7 @@ int kvm_gfn_to_pfn_cache_init(struct kvm *kvm, struct gfn_to_pfn_cache *gpc,
if (!gpc->active) {
rwlock_init(&gpc->lock);
+ mutex_init(&gpc->refresh_lock);
gpc->khva = NULL;
gpc->pfn = KVM_PFN_ERR_FAULT;