diff options
| author | Wanpeng Li <wanpeng.li@hotmail.com> | 2017-12-04 22:21:30 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-12-29 17:53:48 +0100 |
| commit | 41e1386388dc53bc0b9d7744fd1a99567d737fed (patch) | |
| tree | 262df8cb5bbe4fc4bc22fcf08ffe88fc2ea088c6 /arch/x86/kvm/mmu.c | |
| parent | 5aa30b450a8b8b6c8a0921e00e900c0ab9b8c4ae (diff) | |
KVM: MMU: Fix infinite loop when there is no available mmu page
commit ed52870f4676489124d8697fd00e6ae6c504e586 upstream.
The below test case can cause infinite loop in kvm when ept=0.
#include <unistd.h>
#include <sys/syscall.h>
#include <string.h>
#include <stdint.h>
#include <linux/kvm.h>
#include <fcntl.h>
#include <sys/ioctl.h>
long r[5];
int main()
{
r[2] = open("/dev/kvm", O_RDONLY);
r[3] = ioctl(r[2], KVM_CREATE_VM, 0);
r[4] = ioctl(r[3], KVM_CREATE_VCPU, 7);
ioctl(r[4], KVM_RUN, 0);
}
It doesn't setup the memory regions, mmu_alloc_shadow/direct_roots() in
kvm return 1 when kvm fails to allocate root page table which can result
in beblow infinite loop:
vcpu_run() {
for (;;) {
r = vcpu_enter_guest()::kvm_mmu_reload() returns 1
if (r <= 0)
break;
if (need_resched())
cond_resched();
}
}
This patch fixes it by returning -ENOSPC when there is no available kvm mmu
page for root page table.
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Fixes: 26eeb53cf0f (KVM: MMU: Bail out immediately if there is no available mmu page)
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/x86/kvm/mmu.c')
| -rw-r--r-- | arch/x86/kvm/mmu.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 13ebeedcec07..0fce8d73403c 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -3382,7 +3382,7 @@ static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu) spin_lock(&vcpu->kvm->mmu_lock); if(make_mmu_pages_available(vcpu) < 0) { spin_unlock(&vcpu->kvm->mmu_lock); - return 1; + return -ENOSPC; } sp = kvm_mmu_get_page(vcpu, 0, 0, vcpu->arch.mmu.shadow_root_level, 1, ACC_ALL); @@ -3397,7 +3397,7 @@ static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu) spin_lock(&vcpu->kvm->mmu_lock); if (make_mmu_pages_available(vcpu) < 0) { spin_unlock(&vcpu->kvm->mmu_lock); - return 1; + return -ENOSPC; } sp = kvm_mmu_get_page(vcpu, i << (30 - PAGE_SHIFT), i << 30, PT32_ROOT_LEVEL, 1, ACC_ALL); @@ -3437,7 +3437,7 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu) spin_lock(&vcpu->kvm->mmu_lock); if (make_mmu_pages_available(vcpu) < 0) { spin_unlock(&vcpu->kvm->mmu_lock); - return 1; + return -ENOSPC; } sp = kvm_mmu_get_page(vcpu, root_gfn, 0, vcpu->arch.mmu.shadow_root_level, 0, ACC_ALL); @@ -3474,7 +3474,7 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu) spin_lock(&vcpu->kvm->mmu_lock); if (make_mmu_pages_available(vcpu) < 0) { spin_unlock(&vcpu->kvm->mmu_lock); - return 1; + return -ENOSPC; } sp = kvm_mmu_get_page(vcpu, root_gfn, i << 30, PT32_ROOT_LEVEL, 0, ACC_ALL); |