| From 8b3405e345b5a098101b0c31b264c812bba045d9 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: kvm: arm/arm64: Fix locking for kvm_free_stage2_pgd |
| |
| From: Suzuki K Poulose <suzuki.poulose@arm.com> |
| |
| 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 <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: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| arch/arm/kvm/mmu.c | 12 ++++++++++++ |
| 1 file changed, 12 insertions(+) |
| |
| --- a/arch/arm/kvm/mmu.c |
| +++ b/arch/arm/kvm/mmu.c |
| @@ -300,6 +300,14 @@ 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 we are dealing with a large range in |
| + * stage2 table, 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); |
| } |
| |
| @@ -738,6 +746,7 @@ 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); |
| } |
| |
| @@ -824,7 +833,10 @@ 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); |
| + |
| kvm_free_hwpgd(kvm_get_hwpgd(kvm)); |
| if (KVM_PREALLOC_LEVEL > 0) |
| kfree(kvm->arch.pgd); |