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KVM: Drop kvm_reload_remote_mmus(), open code request in x86 users

Remove the generic kvm_reload_remote_mmus() and open code its functionality into the two x86 callers. x86 is (obviously) the only architecture that uses the hook, and is also the only architecture that uses KVM_REQ_MMU_RELOAD in a way that's consistent with the name. That will change in a future patch, as x86's usage when zapping a single shadow page x86 doesn't actually _need_ to reload all vCPUs' MMUs, only MMUs whose root is being zapped actually need to be reloaded. s390 also uses KVM_REQ_MMU_RELOAD, but for a slightly different purpose. Drop the generic code in anticipation of implementing s390 and x86 arch specific requests, which will allow dropping KVM_REQ_MMU_RELOAD entirely. Opportunistically reword the x86 TDP MMU comment to avoid making references to functions (and requests!) when possible, and to remove the rather ambiguous "this". No functional change intended.

Sean Christopherson committed 4 years ago

Commit 2f6f66c1 parent f6d0a253 files · +7 −13Browse files

Unified · Split

3 files
  1. arch/x86/kvm/mmu/mmu.c +7 −7
  2. include/linux/kvm_host.h +0 −1
  3. virt/kvm/kvm_main.c +0 −5
arch/x86/kvm/mmu/mmu.c+7−7
@@ -2353,7 +2353,7 @@ static bool __kvm_mmu_prepare_zap_page(struct kvm *kvm, · 2352 unmodified lines
23532353 * treats invalid shadow pages as being obsolete.
23542354 */
23552355 if (!is_obsolete_sp(kvm, sp))
2356− kvm_reload_remote_mmus(kvm);
2356+ kvm_make_all_cpus_request(kvm, KVM_REQ_MMU_RELOAD);
23572357 }
23582358
23592359 if (sp->lpage_disallowed)
@@ -5639,11 +5639,11 @@ static void kvm_mmu_zap_all_fast(struct kvm *kvm) · 3279 unmodified lines
56395639 */
56405640 kvm->arch.mmu_valid_gen = kvm->arch.mmu_valid_gen ? 0 : 1;
56415641
5642− /* In order to ensure all threads see this change when
5643− * handling the MMU reload signal, this must happen in the
5644− * same critical section as kvm_reload_remote_mmus, and
5645− * before kvm_zap_obsolete_pages as kvm_zap_obsolete_pages
5646− * could drop the MMU lock and yield.
5642+ /*
5643+ * In order to ensure all vCPUs drop their soon-to-be invalid roots,
5644+ * invalidating TDP MMU roots must be done while holding mmu_lock for
5645+ * write and in the same critical section as making the reload request,
5646+ * e.g. before kvm_zap_obsolete_pages() could drop mmu_lock and yield.
56475647 */
56485648 if (is_tdp_mmu_enabled(kvm))
56495649 kvm_tdp_mmu_invalidate_all_roots(kvm);
@@ -5656,7 +5656,7 @@ static void kvm_mmu_zap_all_fast(struct kvm *kvm) · 6 unmodified lines
56565656 * Note: we need to do this under the protection of mmu_lock,
56575657 * otherwise, vcpu would purge shadow page but miss tlb flush.
56585658 */
5659− kvm_reload_remote_mmus(kvm);
5659+ kvm_make_all_cpus_request(kvm, KVM_REQ_MMU_RELOAD);
56605660
56615661 kvm_zap_obsolete_pages(kvm);
56625662
include/linux/kvm_host.h+0−1
@@ -1325,7 +1325,6 @@ int kvm_vcpu_yield_to(struct kvm_vcpu *target); · 1324 unmodified lines
13251325 void kvm_vcpu_on_spin(struct kvm_vcpu *vcpu, bool usermode_vcpu_not_eligible);
13261326
13271327 void kvm_flush_remote_tlbs(struct kvm *kvm);
1328−void kvm_reload_remote_mmus(struct kvm *kvm);
13291328
13301329 #ifdef KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE
13311330 int kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int min);
virt/kvm/kvm_main.c+0−5
@@ -354,11 +354,6 @@ void kvm_flush_remote_tlbs(struct kvm *kvm) · 353 unmodified lines
354354 EXPORT_SYMBOL_GPL(kvm_flush_remote_tlbs);
355355 #endif
356356
357−void kvm_reload_remote_mmus(struct kvm *kvm)
358−{
359− kvm_make_all_cpus_request(kvm, KVM_REQ_MMU_RELOAD);
360−}
361−
362357 #ifdef KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE
363358 static inline void *mmu_memory_cache_alloc_obj(struct kvm_mmu_memory_cache *mc,
364359 gfp_t gfp_flags)

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