[PULL 0/1] KVM: s390: urgent fix for kvm/next

[PULL 0/1] KVM: s390: urgent fix for kvm/next

[Christian Borntraeger]

Paolo,

here is a fix for a regression that is in current kvm/next, which is
targetted for 3.14. Please apply

Christian Borntraeger (1):
  KVM: s390: Fix memory access error detection

 arch/s390/kvm/kvm-s390.c |    4 ++++
 1 file changed, 4 insertions(+)

-- 
1.7.9.5

The following changes since commit 26a865f4aa8e66a6d94958de7656f7f1b03c6c56:

  KVM: VMX: fix use after free of vmx->loaded_vmcs (2014-01-08 19:14:08 -0200)

are available in the git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux.git kvm-urgent

for you to fetch changes up to 699bde3b6c95319749a8e1b7aa2b3f6bee84bff8:

  KVM: s390: Fix memory access error detection (2014-01-20 12:34:13 +0100)

----------------------------------------------------------------
Christian Borntraeger (1):
      KVM: s390: Fix memory access error detection

 arch/s390/kvm/kvm-s390.c |    4 ++++
 1 file changed, 4 insertions(+)

[PULL 1/1] KVM: s390: Fix memory access error detection

[Christian Borntraeger]

Seems that commit 210b1607012cc9034841a393e0591b2c86d9e26c
(KVM: s390: Removed SIE_INTERCEPT_UCONTROL) lost a hunk when we
reworked our patch queue to rework the async_fp code. We now
ignore faults on the sie instruction (guest accesses non-existing
memory) instead of sending a fault into the guest. This leads to
hang situations with the old virtio transport that checks for
descriptor memory after guest memory. Instead of bailing out this
code now goes wild...
Lets re-add the check.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
 arch/s390/kvm/kvm-s390.c |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 1bb1dda..7635c00 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -738,6 +738,10 @@ static int vcpu_post_run(struct kvm_vcpu *vcpu, int exit_reason)
 						current->thread.gmap_addr;
 		vcpu->run->s390_ucontrol.pgm_code = 0x10;
 		rc = -EREMOTE;
+	} else {
+		VCPU_EVENT(vcpu, 3, "%s", "fault in sie instruction");
+		trace_kvm_s390_sie_fault(vcpu);
+		rc = kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
 	}
 
 	memcpy(&vcpu->run->s.regs.gprs[14], &vcpu->arch.sie_block->gg14, 16);
-- 
1.7.9.5

Re: [PULL 0/1] KVM: s390: urgent fix for kvm/next

[Paolo Bonzini]

Il 20/01/2014 12:54, Christian Borntraeger ha scritto:
> Paolo,
> 
> here is a fix for a regression that is in current kvm/next, which is
> targetted for 3.14. Please apply
> 
> Christian Borntraeger (1):
>   KVM: s390: Fix memory access error detection
> 
>  arch/s390/kvm/kvm-s390.c |    4 ++++
>  1 file changed, 4 insertions(+)
> 

Thanks, will pull before sending to Linus (which will probably happen
tomorrow anyway).

Paolo

Re: [PULL 1/1] KVM: s390: Fix memory access error detection

[Cornelia Huck]

On Mon, 20 Jan 2014 12:54:03 +0100
Christian Borntraeger <borntraeger@de.ibm.com> wrote:

> Seems that commit 210b1607012cc9034841a393e0591b2c86d9e26c
> (KVM: s390: Removed SIE_INTERCEPT_UCONTROL) lost a hunk when we
> reworked our patch queue to rework the async_fp code. We now
> ignore faults on the sie instruction (guest accesses non-existing
> memory) instead of sending a fault into the guest. This leads to
> hang situations with the old virtio transport that checks for
> descriptor memory after guest memory. Instead of bailing out this
> code now goes wild...
> Lets re-add the check.
> 
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>

> ---
>  arch/s390/kvm/kvm-s390.c |    4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index 1bb1dda..7635c00 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -738,6 +738,10 @@ static int vcpu_post_run(struct kvm_vcpu *vcpu, int exit_reason)
>  						current->thread.gmap_addr;
>  		vcpu->run->s390_ucontrol.pgm_code = 0x10;
>  		rc = -EREMOTE;
> +	} else {
> +		VCPU_EVENT(vcpu, 3, "%s", "fault in sie instruction");
> +		trace_kvm_s390_sie_fault(vcpu);
> +		rc = kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
>  	}
> 
>  	memcpy(&vcpu->run->s.regs.gprs[14], &vcpu->arch.sie_block->gg14, 16);