Received-SPF: pass (google.com: domain of linux-kernel+bounces-208248-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45d1:ec00::1 as permitted sender) client-ip=2604:1380:45d1:ec00::1;
From: Steven Price <steven.price@arm.com>
To: kvm@vger.kernel.org,
	kvmarm@lists.linux.dev
Cc: Sean Christopherson <seanjc@google.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Marc Zyngier <maz@kernel.org>,
	Will Deacon <will@kernel.org>,
	James Morse <james.morse@arm.com>,
	Oliver Upton <oliver.upton@linux.dev>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Zenghui Yu <yuzenghui@huawei.com>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	Joey Gouly <joey.gouly@arm.com>,
	Alexandru Elisei <alexandru.elisei@arm.com>,
	Christoffer Dall <christoffer.dall@arm.com>,
	Fuad Tabba <tabba@google.com>,
	linux-coco@lists.linux.dev,
	Ganapatrao Kulkarni <gankulkarni@os.amperecomputing.com>,
	Steven Price <steven.price@arm.com>
Subject: [PATCH v3 01/43] KVM: Prepare for handling only shared mappings in mmu_notifier events
Date: Mon, 10 Jun 2024 14:41:20 +0100
Message-Id: <20240610134202.54893-2-steven.price@arm.com>
In-Reply-To: <20240610134202.54893-1-steven.price@arm.com>
References: <20240610134202.54893-1-steven.price@arm.com>
Precedence: bulk
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit

From: Sean Christopherson <seanjc@google.com>

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/ZJX0hk+KpQP0KUyB@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Steven Price <steven.price@arm.com>
---
 include/linux/kvm_host.h | 2 ++
 virt/kvm/kvm_main.c      | 7 +++++++
 2 files changed, 9 insertions(+)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 692c01e41a18..c5394c948db5 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 14841acb8b95..ff486d7d29b4 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -634,6 +634,13 @@ 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;
 
 			/*
-- 
2.34.1