Sorry for the late review...
On 11/21/21 13:54, David Woodhouse wrote:
+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, bool dirty)
+{
+ /* 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));
+#ifdef CONFIG_HAS_IOMEM
+ else
+ memunmap(khva);
+#endif
+ }
Considering that the khva is passed directly to memunmap, perhaps it's
cleaner to ensure it's page-aligned:
diff --git a/virt/kvm/pfncache.c b/virt/kvm/pfncache.c
index 13cae72d39e9..267477bd2972 100644
--- a/virt/kvm/pfncache.c
+++ b/virt/kvm/pfncache.c
@@ -147,7 +147,7 @@ int kvm_gfn_to_pfn_cache_refresh(struct kvm *kvm, struct gfn_to_pfn_cache *gpc,
old_gpa = gpc->gpa;
old_pfn = gpc->pfn;
- old_khva = gpc->khva;
+ old_khva = (void *)((unsigned long)gpc->khva & ~PAGE_MASK);
old_uhva = gpc->uhva;
old_valid = gpc->valid;
old_dirty = gpc->dirty;
@@ -209,7 +209,7 @@ int kvm_gfn_to_pfn_cache_refresh(struct kvm *kvm, struct gfn_to_pfn_cache *gpc,
if (gpc->kernel_map) {
if (new_pfn == old_pfn) {
- new_khva = (void *)((unsigned long)old_khva - page_offset);
+ new_khva = old_khva;
old_pfn = KVM_PFN_ERR_FAULT;
old_khva = NULL;
} else if (pfn_valid(new_pfn)) {
@@ -265,7 +265,7 @@ void kvm_gfn_to_pfn_cache_unmap(struct kvm *kvm, struct gfn_to_pfn_cache *gpc)
gpc->valid = false;
- old_khva = gpc->khva;
+ old_khva = (void *)((unsigned long)gpc->khva & ~PAGE_MASK);
old_dirty = gpc->dirty;
old_gpa = gpc->gpa;
old_pfn = gpc->pfn;
+ retry_map:
+ mmu_seq = kvm->mmu_notifier_seq;
+ smp_rmb();
+
+ /* We always request a writeable mapping */
+ new_pfn = hva_to_pfn(uhva, false, NULL, true, NULL);
+ if (is_error_noslot_pfn(new_pfn)) {
+ ret = -EFAULT;
+ goto map_done;
+ }
+
+ KVM_MMU_READ_LOCK(kvm);
+ retry = mmu_notifier_retry_hva(kvm, mmu_seq, uhva);
+ KVM_MMU_READ_UNLOCK(kvm);
+ if (retry) {
+ cond_resched();
+ goto retry_map;
+ }
+
This should also be a separate function, like
static kvm_pfn_t hva_to_pfn_retry(unsigned long uhva)
{
kvm_pfn_t new_pfn
unsigned long mmu_seq;
int retry;
retry_map:
mmu_seq = kvm->mmu_notifier_seq;
smp_rmb();
/* We always request a writeable mapping */
new_pfn = hva_to_pfn(uhva, false, NULL, true, NULL);
if (is_error_noslot_pfn(new_pfn))
return new_pfn;
KVM_MMU_READ_LOCK(kvm);
retry = mmu_notifier_retry_hva(kvm, mmu_seq, uhva);
KVM_MMU_READ_UNLOCK(kvm);
if (retry) {
cond_resched();
goto retry_map;
}
return new_pfn;
}
+ 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 + page_offset;
+ }
Should set gpc->khva only if new_khva != NULL (i.e. only if gpc->kernel_map
is true).
Paolo
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