| From e80f58f2326dc4fe7c5a76d39990254cc7863de0 Mon Sep 17 00:00:00 2001 |
| From: Suzuki K Poulose <suzuki.poulose@arm.com> |
| Date: Mon, 3 Apr 2017 15:12:43 +0100 |
| Subject: [PATCH] kvm: arm/arm64: Fix locking for kvm_free_stage2_pgd |
| |
| 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: stable@vger.kernel.org # v3.10+ |
| Cc: Paolo Bonzini <pbonzin@redhat.com> |
| Cc: Marc Zyngier <marc.zyngier@arm.com> |
| Cc: Christoffer Dall <christoffer.dall@linaro.org> |
| Cc: Mark Rutland <mark.rutland@arm.com> |
| Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> |
| [ Avoid vCPU starvation and lockup detector warnings ] |
| Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> |
| Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> |
| Signed-off-by: Christoffer Dall <cdall@linaro.org> |
| Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> |
| |
| diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c |
| index b3063ee63593..5911297093b7 100644 |
| --- a/arch/arm/kvm/mmu.c |
| +++ b/arch/arm/kvm/mmu.c |
| @@ -292,11 +292,18 @@ 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 { |
| next = stage2_pgd_addr_end(addr, end); |
| if (!stage2_pgd_none(*pgd)) |
| unmap_stage2_puds(kvm, pgd, addr, next); |
| + /* |
| + * If the range is too large, release the kvm->mmu_lock |
| + * to prevent starvation and lockup detector warnings. |
| + */ |
| + if (next != end) |
| + cond_resched_lock(&kvm->mmu_lock); |
| } while (pgd++, addr = next, addr != end); |
| } |
| |
| @@ -832,7 +839,10 @@ 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; |
| -- |
| 2.12.0 |
| |