On 18.12.20 15:18, Claudio Imbrenda wrote:
> The addresses in the SIE control block of the host should not be
> forwarded to the guest. They are only meaningful to the host, and
> moreover it would be a clear security issue.
It's really almost impossible for someone without access to
documentation to understand what we leak. I assume we're leaking the g1
address of a page table (entry), used for translation of g2->g3 to g1.
Can you try making that clearer?
In that case, it's pretty much a random number (of a random page used as
a leave page table) and does not let g1 identify locations of symbols
etc. If so, I don't think this is a "clear security issue" and suggest
squashing this into the actual fix (#p4 I assume).
@Christian, @Janosch? Am I missing something?
>
> Subsequent patches will actually put the right values in the guest SIE
> control block.
>
> Fixes: a3508fbe9dc6d ("KVM: s390: vsie: initial support for nested virtualization")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
> ---
> arch/s390/kvm/vsie.c | 5 -----
> 1 file changed, 5 deletions(-)
>
> diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
> index 4f3cbf6003a9..ada49583e530 100644
> --- a/arch/s390/kvm/vsie.c
> +++ b/arch/s390/kvm/vsie.c
> @@ -416,11 +416,6 @@ static void unshadow_scb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
> memcpy((void *)((u64)scb_o + 0xc0),
> (void *)((u64)scb_s + 0xc0), 0xf0 - 0xc0);
> break;
> - case ICPT_PARTEXEC:
> - /* MVPG only */
> - memcpy((void *)((u64)scb_o + 0xc0),
> - (void *)((u64)scb_s + 0xc0), 0xd0 - 0xc0);
> - break;
> }
>
> if (scb_s->ihcpu != 0xffffU)
>
--
Thanks,
David / dhildenb
