On 21/11/2023 22:47, David Woodhouse wrote:
On Tue, 2023-11-21 at 18:02 +0000, Paul Durrant wrote:
-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, u64 addr, bool addr_is_gpa,
unsigned long len)
{
struct kvm_memslots *slots = kvm_memslots(gpc->kvm);
- unsigned long page_offset = offset_in_page(gpa);
+ unsigned long page_offset = offset_in_page(addr);
bool unmap_old = false;
kvm_pfn_t old_pfn;
bool hva_change = false;
@@ -244,12 +244,21 @@ static int __kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, gpa_t gpa,
old_pfn = gpc->pfn;
old_khva = (void *)PAGE_ALIGN_DOWN((uintptr_t)gpc->khva);
- /* If the userspace HVA is invalid, refresh that first */
- if (gpc->gpa != gpa || gpc->generation != slots->generation ||
- kvm_is_error_hva(gpc->uhva)) {
- gfn_t gfn = gpa_to_gfn(gpa);
+ if (!addr_is_gpa) {
+ gpc->gpa = KVM_XEN_INVALID_GPA;
+ gpc->uhva = PAGE_ALIGN_DOWN(gpc->uhva);
+ addr = PAGE_ALIGN_DOWN(addr);
+
+ if (gpc->uhva != addr) {
+ gpc->uhva = addr;
+ hva_change = true;
+ }
+ } else if (gpc->gpa != addr ||
+ gpc->generation != slots->generation ||
+ kvm_is_error_hva(gpc->uhva)) {
+ gfn_t gfn = gpa_to_gfn(addr);
- gpc->gpa = gpa;
+ gpc->gpa = addr;
gpc->generation = slots->generation;
gpc->memslot = __gfn_to_memslot(slots, gfn);
gpc->uhva = gfn_to_hva_memslot(gpc->memslot, gfn);
Hrm, now that a previous patch means we're preserving the low bits of
gpc->uhva surely you don't *need* to mess with the gpc struct?
I'm not messing with it, am I?
If gpc->gpa == KVM_XEN_INVALID_GPA (but gpc->uhva != KVM_ERR_ERR_BAD &&
gpc->active) surely that's enough to signal that gpc->uhva is canonical
and doesn't need to be looked up from the GPA?
And I think that means the 'bool addr_is_gpa' argument can go away from
__kvm_gpc_refresh(); you can set it up in {__,}kvm_gpc_activate*()
instead?
Alas not... __kvm_gpc_refresh() still needs to know *something* has
changed, otherwise the khva will be stale.
Paul
