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authorPaul Durrant <pdurrant@amazon.com>2024-02-15 15:29:04 +0000
committerSean Christopherson <seanjc@google.com>2024-02-20 07:37:46 -0800
commit721f5b0dda784829b833039fbb42f420b9f86575 (patch)
tree28071a513bf7532a3fb3bf005e6aa3c635b3062b /virt
parent9e7325acb3dc8df8a6370ebc18aef107aae17ef0 (diff)
KVM: pfncache: allow a cache to be activated with a fixed (userspace) HVA
Some pfncache pages may actually be overlays on guest memory that have a fixed HVA within the VMM. It's pointless to invalidate such cached mappings if the overlay is moved so allow a cache to be activated directly with the HVA to cater for such cases. A subsequent patch will make use of this facility. Signed-off-by: Paul Durrant <pdurrant@amazon.com> Reviewed-by: David Woodhouse <dwmw@amazon.co.uk> Link: https://lore.kernel.org/r/20240215152916.1158-10-paul@xen.org Signed-off-by: Sean Christopherson <seanjc@google.com>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/pfncache.c98
1 files changed, 70 insertions, 28 deletions
diff --git a/virt/kvm/pfncache.c b/virt/kvm/pfncache.c
index 97eec8ee3449..a47ca6fd75c2 100644
--- a/virt/kvm/pfncache.c
+++ b/virt/kvm/pfncache.c
@@ -48,7 +48,14 @@ bool kvm_gpc_check(struct gfn_to_pfn_cache *gpc, unsigned long len)
if (!gpc->active)
return false;
- if (gpc->generation != slots->generation || kvm_is_error_hva(gpc->uhva))
+ /*
+ * If the page was cached from a memslot, make sure the memslots have
+ * not been re-configured.
+ */
+ if (!kvm_is_error_gpa(gpc->gpa) && gpc->generation != slots->generation)
+ return false;
+
+ if (kvm_is_error_hva(gpc->uhva))
return false;
if (offset_in_page(gpc->uhva) + len > PAGE_SIZE)
@@ -209,11 +216,10 @@ out_error:
return -EFAULT;
}
-static int __kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, gpa_t gpa,
+static int __kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long uhva,
unsigned long len)
{
- struct kvm_memslots *slots = kvm_memslots(gpc->kvm);
- unsigned long page_offset = offset_in_page(gpa);
+ unsigned long page_offset;
bool unmap_old = false;
unsigned long old_uhva;
kvm_pfn_t old_pfn;
@@ -221,10 +227,16 @@ static int __kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, gpa_t gpa,
void *old_khva;
int ret;
+ /* Either gpa or uhva must be valid, but not both */
+ if (WARN_ON_ONCE(kvm_is_error_gpa(gpa) == kvm_is_error_hva(uhva)))
+ return -EINVAL;
+
/*
- * If must fit within a single page. The 'len' argument is
- * only to enforce that.
+ * The cached acces must fit within a single page. The 'len' argument
+ * exists only to enforce that.
*/
+ page_offset = kvm_is_error_gpa(gpa) ? offset_in_page(uhva) :
+ offset_in_page(gpa);
if (page_offset + len > PAGE_SIZE)
return -EINVAL;
@@ -246,29 +258,39 @@ static int __kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, gpa_t gpa,
old_khva = (void *)PAGE_ALIGN_DOWN((uintptr_t)gpc->khva);
old_uhva = PAGE_ALIGN_DOWN(gpc->uhva);
- /* Refresh the userspace HVA if necessary */
- if (gpc->gpa != gpa || gpc->generation != slots->generation ||
- kvm_is_error_hva(gpc->uhva)) {
- gfn_t gfn = gpa_to_gfn(gpa);
-
- gpc->gpa = gpa;
- gpc->generation = slots->generation;
- gpc->memslot = __gfn_to_memslot(slots, gfn);
- gpc->uhva = gfn_to_hva_memslot(gpc->memslot, gfn);
+ if (kvm_is_error_gpa(gpa)) {
+ gpc->gpa = INVALID_GPA;
+ gpc->memslot = NULL;
+ gpc->uhva = PAGE_ALIGN_DOWN(uhva);
- if (kvm_is_error_hva(gpc->uhva)) {
- ret = -EFAULT;
- goto out;
- }
-
- /*
- * Even if the GPA and/or the memslot generation changed, the
- * HVA may still be the same.
- */
if (gpc->uhva != old_uhva)
hva_change = true;
} else {
- gpc->uhva = old_uhva;
+ struct kvm_memslots *slots = kvm_memslots(gpc->kvm);
+
+ if (gpc->gpa != gpa || gpc->generation != slots->generation ||
+ kvm_is_error_hva(gpc->uhva)) {
+ gfn_t gfn = gpa_to_gfn(gpa);
+
+ gpc->gpa = gpa;
+ gpc->generation = slots->generation;
+ gpc->memslot = __gfn_to_memslot(slots, gfn);
+ gpc->uhva = gfn_to_hva_memslot(gpc->memslot, gfn);
+
+ if (kvm_is_error_hva(gpc->uhva)) {
+ ret = -EFAULT;
+ goto out;
+ }
+
+ /*
+ * Even if the GPA and/or the memslot generation changed, the
+ * HVA may still be the same.
+ */
+ if (gpc->uhva != old_uhva)
+ hva_change = true;
+ } else {
+ gpc->uhva = old_uhva;
+ }
}
/* Note: the offset must be correct before calling hva_to_pfn_retry() */
@@ -319,7 +341,15 @@ out_unlock:
int kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, unsigned long len)
{
- return __kvm_gpc_refresh(gpc, gpc->gpa, len);
+ /*
+ * If the GPA is valid then ignore the HVA, as a cache can be GPA-based
+ * or HVA-based, not both. For GPA-based caches, the HVA will be
+ * recomputed during refresh if necessary.
+ */
+ unsigned long uhva = kvm_is_error_gpa(gpc->gpa) ? gpc->uhva :
+ KVM_HVA_ERR_BAD;
+
+ return __kvm_gpc_refresh(gpc, gpc->gpa, uhva, len);
}
void kvm_gpc_init(struct gfn_to_pfn_cache *gpc, struct kvm *kvm)
@@ -329,10 +359,12 @@ void kvm_gpc_init(struct gfn_to_pfn_cache *gpc, struct kvm *kvm)
gpc->kvm = kvm;
gpc->pfn = KVM_PFN_ERR_FAULT;
+ gpc->gpa = INVALID_GPA;
gpc->uhva = KVM_HVA_ERR_BAD;
}
-int kvm_gpc_activate(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long len)
+static int __kvm_gpc_activate(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long uhva,
+ unsigned long len)
{
struct kvm *kvm = gpc->kvm;
@@ -353,7 +385,17 @@ 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, uhva, len);
+}
+
+int kvm_gpc_activate(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long len)
+{
+ return __kvm_gpc_activate(gpc, gpa, KVM_HVA_ERR_BAD, len);
+}
+
+int kvm_gpc_activate_hva(struct gfn_to_pfn_cache *gpc, unsigned long uhva, unsigned long len)
+{
+ return __kvm_gpc_activate(gpc, INVALID_GPA, uhva, len);
}
void kvm_gpc_deactivate(struct gfn_to_pfn_cache *gpc)