1 files changed, 93 insertions, 0 deletions
diff --git a/arch/x86/kvm/kvm_onhyperv.c b/arch/x86/kvm/kvm_onhyperv.c
new file mode 100644
index 000000000000..c7db2df50a7a
--- /dev/null
+++ b/arch/x86/kvm/kvm_onhyperv.c
@@ -0,0 +1,93 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * KVM L1 hypervisor optimizations on Hyper-V.
+ */
+
+#include <linux/kvm_host.h>
+#include <asm/mshyperv.h>
+
+#include "hyperv.h"
+#include "kvm_onhyperv.h"
+
+static int kvm_fill_hv_flush_list_func(struct hv_guest_mapping_flush_list *flush,
+		void *data)
+{
+	struct kvm_tlb_range *range = data;
+
+	return hyperv_fill_flush_guest_mapping_list(flush, range->start_gfn,
+			range->pages);
+}
+
+static inline int hv_remote_flush_root_tdp(hpa_t root_tdp,
+					   struct kvm_tlb_range *range)
+{
+	if (range)
+		return hyperv_flush_guest_mapping_range(root_tdp,
+				kvm_fill_hv_flush_list_func, (void *)range);
+	else
+		return hyperv_flush_guest_mapping(root_tdp);
+}
+
+int hv_remote_flush_tlb_with_range(struct kvm *kvm,
+		struct kvm_tlb_range *range)
+{
+	struct kvm_arch *kvm_arch = &kvm->arch;
+	struct kvm_vcpu *vcpu;
+	int ret = 0, i, nr_unique_valid_roots;
+	hpa_t root;
+
+	spin_lock(&kvm_arch->hv_root_tdp_lock);
+
+	if (!VALID_PAGE(kvm_arch->hv_root_tdp)) {
+		nr_unique_valid_roots = 0;
+
+		/*
+		 * Flush all valid roots, and see if all vCPUs have converged
+		 * on a common root, in which case future flushes can skip the
+		 * loop and flush the common root.
+		 */
+		kvm_for_each_vcpu(i, vcpu, kvm) {
+			root = vcpu->arch.hv_root_tdp;
+			if (!VALID_PAGE(root) || root == kvm_arch->hv_root_tdp)
+				continue;
+
+			/*
+			 * Set the tracked root to the first valid root.  Keep
+			 * this root for the entirety of the loop even if more
+			 * roots are encountered as a low effort optimization
+			 * to avoid flushing the same (first) root again.
+			 */
+			if (++nr_unique_valid_roots == 1)
+				kvm_arch->hv_root_tdp = root;
+
+			if (!ret)
+				ret = hv_remote_flush_root_tdp(root, range);
+
+			/*
+			 * Stop processing roots if a failure occurred and
+			 * multiple valid roots have already been detected.
+			 */
+			if (ret && nr_unique_valid_roots > 1)
+				break;
+		}
+
+		/*
+		 * The optimized flush of a single root can't be used if there
+		 * are multiple valid roots (obviously).
+		 */
+		if (nr_unique_valid_roots > 1)
+			kvm_arch->hv_root_tdp = INVALID_PAGE;
+	} else {
+		ret = hv_remote_flush_root_tdp(kvm_arch->hv_root_tdp, range);
+	}
+
+	spin_unlock(&kvm_arch->hv_root_tdp_lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(hv_remote_flush_tlb_with_range);
+
+int hv_remote_flush_tlb(struct kvm *kvm)
+{
+	return hv_remote_flush_tlb_with_range(kvm, NULL);
+}
+EXPORT_SYMBOL_GPL(hv_remote_flush_tlb);