From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753023AbdDCONK (ORCPT ); Mon, 3 Apr 2017 10:13:10 -0400 Received: from foss.arm.com ([217.140.101.70]:59324 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752290AbdDCONI (ORCPT ); Mon, 3 Apr 2017 10:13:08 -0400 From: Suzuki K Poulose To: linux-arm-kernel@lists.infradead.org, andreyknvl@google.com Cc: dvyukov@google.com, marc.zyngier@arm.com, christoffer.dall@linaro.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, kcc@google.com, syzkaller@googlegroups.com, will.deacon@arm.com, catalin.marinas@arm.com, pbonzini@redhat.com, mark.rutland@arm.com, suzuki.poulose@arm.com, ard.biesheuvel@linaro.org, stable@vger.kernel.org Subject: [PATCH v3] kvm: arm/arm64: Fix locking for kvm_free_stage2_pgd Date: Mon, 3 Apr 2017 15:12:43 +0100 Message-Id: <1491228763-23450-1-git-send-email-suzuki.poulose@arm.com> X-Mailer: git-send-email 2.7.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In kvm_free_stage2_pgd() we don't hold the kvm->mmu_lock while calling unmap_stage2_range() on the entire memory range for the guest. This could cause problems with other callers (e.g, munmap on a memslot) trying to unmap a range. And since we have to unmap the entire Guest memory range holding a spinlock, make sure we yield the lock if necessary, after we unmap each PUD range. Fixes: commit d5d8184d35c9 ("KVM: ARM: Memory virtualization setup") Cc: stable@vger.kernel.org # v3.10+ Cc: Paolo Bonzini Cc: Marc Zyngier Cc: Christoffer Dall Cc: Mark Rutland Signed-off-by: Suzuki K Poulose [ Avoid vCPU starvation and lockup detector warnings ] Signed-off-by: Marc Zyngier Signed-off-by: Suzuki K Poulose --- Changes since V2: - Restrict kvm->mmu_lock relaxation to bigger ranges in unmap_stage2_range(), to avoid possible issues like [0] [0] http://lists.infradead.org/pipermail/linux-arm-kernel/2017-March/498210.html Changes since V1: - Yield the kvm->mmu_lock if necessary in unmap_stage2_range to prevent vCPU starvation and lockup detector warnings. --- arch/arm/kvm/mmu.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c index 13b9c1f..db94f3a 100644 --- a/arch/arm/kvm/mmu.c +++ b/arch/arm/kvm/mmu.c @@ -292,8 +292,15 @@ static void unmap_stage2_range(struct kvm *kvm, phys_addr_t start, u64 size) phys_addr_t addr = start, end = start + size; phys_addr_t next; + assert_spin_locked(&kvm->mmu_lock); pgd = kvm->arch.pgd + stage2_pgd_index(addr); do { + /* + * If the range is too large, release the kvm->mmu_lock + * to prevent starvation and lockup detector warnings. + */ + if (size > S2_PUD_SIZE) + cond_resched_lock(&kvm->mmu_lock); next = stage2_pgd_addr_end(addr, end); if (!stage2_pgd_none(*pgd)) unmap_stage2_puds(kvm, pgd, addr, next); @@ -831,7 +838,10 @@ void kvm_free_stage2_pgd(struct kvm *kvm) if (kvm->arch.pgd == NULL) return; + spin_lock(&kvm->mmu_lock); unmap_stage2_range(kvm, 0, KVM_PHYS_SIZE); + spin_unlock(&kvm->mmu_lock); + /* Free the HW pgd, one page at a time */ free_pages_exact(kvm->arch.pgd, S2_PGD_SIZE); kvm->arch.pgd = NULL; -- 2.7.4