[v4,01/43] KVM: Prepare for handling only shared mappings in mmu_notifier events

Commit Message

Steven Price Aug. 21, 2024, 3:38 p.m. UTC

From: Sean Christopherson <[e-mail]>

Add flags to "struct kvm_gfn_range" to let notifier events target only
shared and only private mappings, and write up the existing mmu_notifier
events to be shared-only (private memory is never associated with a
userspace virtual address, i.e. can't be reached via mmu_notifiers).

Add two flags so that KVM can handle the three possibilities (shared,
private, and shared+private) without needing something like a tri-state
enum.

Link: https://lore.kernel.org/all/[e-mail]
Signed-off-by: Sean Christopherson <[e-mail]>
Signed-off-by: Steven Price <[e-mail]>
---
 include/linux/kvm_host.h | 2 ++
 virt/kvm/kvm_main.c      | 7 +++++++
 2 files changed, 9 insertions(+)

Patch

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 689e8be873a7..7393377c7656 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -265,6 +265,8 @@  struct kvm_gfn_range {
 	gfn_t start;
 	gfn_t end;
 	union kvm_mmu_notifier_arg arg;
+	bool only_private;
+	bool only_shared;
 	bool may_block;
 };
 bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index d0788d0a72cc..eaf16195b104 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -631,6 +631,13 @@  static __always_inline kvm_mn_ret_t __kvm_handle_hva_range(struct kvm *kvm,
 			 * the second or later invocation of the handler).
 			 */
 			gfn_range.arg = range->arg;
+
+			/*
+			 * HVA-based notifications aren't relevant to private
+			 * mappings as they don't have a userspace mapping.
+			 */
+			gfn_range.only_private = false;
+			gfn_range.only_shared = true;
 			gfn_range.may_block = range->may_block;
 
 			/*