Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752502AbdGPOIV (ORCPT ); Sun, 16 Jul 2017 10:08:21 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:43232 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751767AbdGPN55 (ORCPT ); Sun, 16 Jul 2017 09:57:57 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Mark Rutland" , "Paolo Bonzini" , "Suzuki K Poulose" , "Christoffer Dall" , "Marc Zyngier" , "Christoffer Dall" Date: Sun, 16 Jul 2017 14:56:46 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 121/178] kvm: arm/arm64: Fix locking for kvm_free_stage2_pgd In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2450 Lines: 69 3.16.46-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Suzuki K Poulose commit 8b3405e345b5a098101b0c31b264c812bba045d9 upstream. 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: 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 Signed-off-by: Christoffer Dall [bwh: Backported to 3.16: - unmap_stage2_range() is a wrapper around unmap_range(), which is also used for HYP page table setup. So unmap_range() should do the cond_resched_lock(), but only if kvm != NULL. - Adjust context] Signed-off-by: Ben Hutchings --- arch/arm/kvm/mmu.c | 10 ++++++++++ 1 file changed, 10 insertions(+) --- a/arch/arm/kvm/mmu.c +++ b/arch/arm/kvm/mmu.c @@ -199,6 +199,12 @@ static void unmap_range(struct kvm *kvm, next = kvm_pgd_addr_end(addr, end); if (!pgd_none(*pgd)) unmap_puds(kvm, pgd, addr, next); + /* + * If the range is too large, release the kvm->mmu_lock + * to prevent starvation and lockup detector warnings. + */ + if (kvm && next != end) + cond_resched_lock(&kvm->mmu_lock); } while (pgd++, addr = next, addr != end); } @@ -553,6 +559,7 @@ int kvm_alloc_stage2_pgd(struct kvm *kvm */ static void unmap_stage2_range(struct kvm *kvm, phys_addr_t start, u64 size) { + assert_spin_locked(&kvm->mmu_lock); unmap_range(kvm, kvm->arch.pgd, start, size); } @@ -637,7 +644,10 @@ 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_pages((unsigned long)kvm->arch.pgd, S2_PGD_ORDER); kvm->arch.pgd = NULL; }