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authorPaul Durrant <pdurrant@amazon.com>2024-02-15 15:29:00 +0000
committerSean Christopherson <seanjc@google.com>2024-02-20 07:37:43 -0800
commita4bff3df51472f555ab8dea05a3d2faf4abbf199 (patch)
tree7e692f20f629b2bd95844e42f86d2e38beb7016a /virt
parent78b74638eb6dffd9b24bc3b121556a9039292df6 (diff)
KVM: pfncache: remove KVM_GUEST_USES_PFN usage
As noted in [1] the KVM_GUEST_USES_PFN usage flag is never set by any callers of kvm_gpc_init(), and for good reason: the implementation is incomplete/broken. And it's not clear that there will ever be a user of KVM_GUEST_USES_PFN, as coordinating vCPUs with mmu_notifier events is non-trivial. Remove KVM_GUEST_USES_PFN and all related code, e.g. dropping KVM_GUEST_USES_PFN also makes the 'vcpu' argument redundant, to avoid having to reason about broken code as __kvm_gpc_refresh() evolves. Moreover, all existing callers specify KVM_HOST_USES_PFN so the usage check in hva_to_pfn_retry() and hence the 'usage' argument to kvm_gpc_init() are also redundant. [1] https://lore.kernel.org/all/ZQiR8IpqOZrOpzHC@google.com Signed-off-by: Paul Durrant <pdurrant@amazon.com> Reviewed-by: David Woodhouse <dwmw@amazon.co.uk> Link: https://lore.kernel.org/r/20240215152916.1158-6-paul@xen.org [sean: explicitly call out that guest usage is incomplete] Signed-off-by: Sean Christopherson <seanjc@google.com>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/pfncache.c61
1 files changed, 9 insertions, 52 deletions
diff --git a/virt/kvm/pfncache.c b/virt/kvm/pfncache.c
index f3571f44d9af..6f4b537eb25b 100644
--- a/virt/kvm/pfncache.c
+++ b/virt/kvm/pfncache.c
@@ -25,9 +25,7 @@
void gfn_to_pfn_cache_invalidate_start(struct kvm *kvm, unsigned long start,
unsigned long end, bool may_block)
{
- DECLARE_BITMAP(vcpu_bitmap, KVM_MAX_VCPUS);
struct gfn_to_pfn_cache *gpc;
- bool evict_vcpus = false;
spin_lock(&kvm->gpc_lock);
list_for_each_entry(gpc, &kvm->gpc_list, list) {
@@ -37,43 +35,10 @@ void gfn_to_pfn_cache_invalidate_start(struct kvm *kvm, unsigned long start,
if (gpc->valid && !is_error_noslot_pfn(gpc->pfn) &&
gpc->uhva >= start && gpc->uhva < end) {
gpc->valid = false;
-
- /*
- * If a guest vCPU could be using the physical address,
- * it needs to be forced out of guest mode.
- */
- if (gpc->usage & KVM_GUEST_USES_PFN) {
- if (!evict_vcpus) {
- evict_vcpus = true;
- bitmap_zero(vcpu_bitmap, KVM_MAX_VCPUS);
- }
- __set_bit(gpc->vcpu->vcpu_idx, vcpu_bitmap);
- }
}
write_unlock_irq(&gpc->lock);
}
spin_unlock(&kvm->gpc_lock);
-
- if (evict_vcpus) {
- /*
- * KVM needs to ensure the vCPU is fully out of guest context
- * before allowing the invalidation to continue.
- */
- unsigned int req = KVM_REQ_OUTSIDE_GUEST_MODE;
- bool called;
-
- /*
- * If the OOM reaper is active, then all vCPUs should have
- * been stopped already, so perform the request without
- * KVM_REQUEST_WAIT and be sad if any needed to be IPI'd.
- */
- if (!may_block)
- req &= ~KVM_REQUEST_WAIT;
-
- called = kvm_make_vcpus_request_mask(kvm, req, vcpu_bitmap);
-
- WARN_ON_ONCE(called && !may_block);
- }
}
bool kvm_gpc_check(struct gfn_to_pfn_cache *gpc, unsigned long len)
@@ -206,16 +171,14 @@ static kvm_pfn_t hva_to_pfn_retry(struct gfn_to_pfn_cache *gpc)
* 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
- new_khva = gpc_map(new_pfn);
-
- if (!new_khva) {
- kvm_release_pfn_clean(new_pfn);
- goto out_error;
- }
+ if (new_pfn == gpc->pfn)
+ new_khva = old_khva;
+ else
+ new_khva = gpc_map(new_pfn);
+
+ if (!new_khva) {
+ kvm_release_pfn_clean(new_pfn);
+ goto out_error;
}
write_lock_irq(&gpc->lock);
@@ -346,18 +309,12 @@ int kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, unsigned long len)
return __kvm_gpc_refresh(gpc, gpc->gpa, len);
}
-void kvm_gpc_init(struct gfn_to_pfn_cache *gpc, struct kvm *kvm,
- struct kvm_vcpu *vcpu, enum pfn_cache_usage usage)
+void kvm_gpc_init(struct gfn_to_pfn_cache *gpc, struct kvm *kvm)
{
- WARN_ON_ONCE(!usage || (usage & KVM_GUEST_AND_HOST_USE_PFN) != usage);
- WARN_ON_ONCE((usage & KVM_GUEST_USES_PFN) && !vcpu);
-
rwlock_init(&gpc->lock);
mutex_init(&gpc->refresh_lock);
gpc->kvm = kvm;
- gpc->vcpu = vcpu;
- gpc->usage = usage;
gpc->pfn = KVM_PFN_ERR_FAULT;
gpc->uhva = KVM_HVA_ERR_BAD;
}