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Mon, 04 May 2026 15:42:41 -0700 (PDT) Date: Mon, 4 May 2026 22:42:10 +0000 In-Reply-To: <20260504224213.1049426-1-jthoughton@google.com> Mime-Version: 1.0 References: <20260504224213.1049426-1-jthoughton@google.com> X-Mailer: git-send-email 2.54.0.545.g6539524ca2-goog Message-ID: <20260504224213.1049426-4-jthoughton@google.com> Subject: [PATCH 3/5] KVM: mips: Grab MMU lock in kvm_arch_flush_shadow_all() From: James Houghton To: Paolo Bonzini Cc: Marc Zyngier , Oliver Upton , Joey Gouly , Suzuki K Poulose , Zenghui Yu , Sean Christopherson , Gavin Shan , Shaoqin Huang , Ricardo Koller , Tianrui Zhao , Bibo Mao , Huacai Chen , James Hogan , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, James Houghton , stable@vger.kernel.org Content-Type: text/plain; charset="UTF-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260504_154243_672298_DFBEAA86 X-CRM114-Status: GOOD ( 10.57 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org kvm_mips_flush_gpa_pt() expects the MMU lock to be held; it is not in this path. This can lead to a double-free of page table entries if kvm_arch_flush_shadow_all() is called twice on the same `kvm` concurrently; such a scenario is possible. Cc: stable@vger.kernel.org Fixes: b62091108633 ("KVM: MIPS: Implement kvm_arch_flush_shadow_all/memslot") Signed-off-by: James Houghton --- Note: This is compile-tested only! arch/mips/kvm/mips.c | 2 ++ arch/mips/kvm/mmu.c | 2 ++ 2 files changed, 4 insertions(+) diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c index a53abbba43ea..463b6c4aa62c 100644 --- a/arch/mips/kvm/mips.c +++ b/arch/mips/kvm/mips.c @@ -180,6 +180,8 @@ long kvm_arch_dev_ioctl(struct file *filp, unsigned int ioctl, void kvm_arch_flush_shadow_all(struct kvm *kvm) { + guard(spinlock)(&kvm->mmu_lock); + /* Flush whole GPA */ kvm_mips_flush_gpa_pt(kvm, 0, ~0); kvm_flush_remote_tlbs(kvm); diff --git a/arch/mips/kvm/mmu.c b/arch/mips/kvm/mmu.c index d2c3b6b41f18..5045833f8116 100644 --- a/arch/mips/kvm/mmu.c +++ b/arch/mips/kvm/mmu.c @@ -269,6 +269,8 @@ static bool kvm_mips_flush_gpa_pgd(pgd_t *pgd, unsigned long start_gpa, */ bool kvm_mips_flush_gpa_pt(struct kvm *kvm, gfn_t start_gfn, gfn_t end_gfn) { + lockdep_assert_held(&kvm->mmu_lock); + return kvm_mips_flush_gpa_pgd(kvm->arch.gpa_mm.pgd, start_gfn << PAGE_SHIFT, end_gfn << PAGE_SHIFT); -- 2.54.0.545.g6539524ca2-goog