[PATCH 6/7] KVM: Allow range-based TLB invalidation from common code

[David Matlack]

Make kvm_flush_remote_tlbs_range() visible in common code and create a
default implementation that just invalidates the whole TLB.

This paves the way for several future cleanups:
 - Introduction of range-based TLBI on ARM.
 - Eliminating kvm_arch_flush_remote_tlbs_memslot()
 - Moving the KVM/x86 TDP MMU to common code.

No functional change intended.

Signed-off-by: David Matlack <dmatlack at google.com>
---
 arch/x86/include/asm/kvm_host.h |  3 +++
 arch/x86/kvm/mmu/mmu.c          |  5 ++---
 arch/x86/kvm/mmu/mmu_internal.h |  1 -
 include/linux/kvm_host.h        |  9 +++++++++
 virt/kvm/kvm_main.c             | 13 +++++++++++++
 5 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 1bacc3de2432..420713ac8916 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1799,6 +1799,9 @@ static inline int kvm_arch_flush_remote_tlbs(struct kvm *kvm)
 		return -ENOTSUPP;
 }
 
+#define __KVM_HAVE_ARCH_FLUSH_REMOTE_TLBS_RANGE
+int kvm_arch_flush_remote_tlbs_range(struct kvm *kvm, gfn_t start_gfn, u64 pages);
+
 #define kvm_arch_pmi_in_guest(vcpu) \
 	((vcpu) && (vcpu)->arch.handling_intr_from_guest)
 
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 1e2c2d711dbb..491c28d22cbe 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -246,7 +246,7 @@ static inline bool kvm_available_flush_tlb_with_range(void)
 	return kvm_x86_ops.tlb_remote_flush_with_range;
 }
 
-void kvm_flush_remote_tlbs_range(struct kvm *kvm, gfn_t start_gfn, u64 pages)
+int kvm_arch_flush_remote_tlbs_range(struct kvm *kvm, gfn_t start_gfn, u64 pages)
 {
 	struct kvm_tlb_range range;
 	int ret = -EOPNOTSUPP;
@@ -257,8 +257,7 @@ void kvm_flush_remote_tlbs_range(struct kvm *kvm, gfn_t start_gfn, u64 pages)
 	if (kvm_x86_ops.tlb_remote_flush_with_range)
 		ret = static_call(kvm_x86_tlb_remote_flush_with_range)(kvm, &range);
 
-	if (ret)
-		kvm_flush_remote_tlbs(kvm);
+	return ret;
 }
 
 static void mark_mmio_spte(struct kvm_vcpu *vcpu, u64 *sptep, u64 gfn,
diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h
index 851982a25502..d5599f2d3f96 100644
--- a/arch/x86/kvm/mmu/mmu_internal.h
+++ b/arch/x86/kvm/mmu/mmu_internal.h
@@ -164,7 +164,6 @@ void kvm_mmu_gfn_allow_lpage(const struct kvm_memory_slot *slot, gfn_t gfn);
 bool kvm_mmu_slot_gfn_write_protect(struct kvm *kvm,
 				    struct kvm_memory_slot *slot, u64 gfn,
 				    int min_level);
-void kvm_flush_remote_tlbs_range(struct kvm *kvm, gfn_t start_gfn, u64 pages);
 unsigned int pte_list_count(struct kvm_rmap_head *rmap_head);
 
 extern int nx_huge_pages;
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 76711afe4d17..acfb17d9b44d 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1356,6 +1356,7 @@ int kvm_vcpu_yield_to(struct kvm_vcpu *target);
 void kvm_vcpu_on_spin(struct kvm_vcpu *vcpu, bool usermode_vcpu_not_eligible);
 
 void kvm_flush_remote_tlbs(struct kvm *kvm);
+void kvm_flush_remote_tlbs_range(struct kvm *kvm, gfn_t gfn, u64 pages);
 
 #ifdef KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE
 int kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int min);
@@ -1484,6 +1485,14 @@ static inline int kvm_arch_flush_remote_tlbs(struct kvm *kvm)
 }
 #endif
 
+#ifndef __KVM_HAVE_ARCH_FLUSH_REMOTE_TLBS_RANGE
+static inline int kvm_arch_flush_remote_tlbs_range(struct kvm *kvm,
+						   gfn_t gfn, u64 pages)
+{
+	return -EOPNOTSUPP;
+}
+#endif
+
 #ifdef __KVM_HAVE_ARCH_NONCOHERENT_DMA
 void kvm_arch_register_noncoherent_dma(struct kvm *kvm);
 void kvm_arch_unregister_noncoherent_dma(struct kvm *kvm);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index fefd3e3c8fe1..c9fc693a39d9 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -368,6 +368,19 @@ void kvm_flush_remote_tlbs(struct kvm *kvm)
 }
 EXPORT_SYMBOL_GPL(kvm_flush_remote_tlbs);
 
+void kvm_flush_remote_tlbs_range(struct kvm *kvm, gfn_t gfn, u64 pages)
+{
+	if (!kvm_arch_flush_remote_tlbs_range(kvm, gfn, pages))
+		return;
+
+	/*
+	 * Fall back to a flushing entire TLBs if the architecture range-based
+	 * TLB invalidation is unsupported or can't be performed for whatever
+	 * reason.
+	 */
+	kvm_flush_remote_tlbs(kvm);
+}
+
 static void kvm_flush_shadow_all(struct kvm *kvm)
 {
 	kvm_arch_flush_shadow_all(kvm);
-- 
2.39.0.246.g2a6d74b583-goog