Re: [PATCH 1/1] KVM: s390: fix LPSWEY handling

[Christian Borntraeger <borntraeger@linux.ibm.com>]

Am 28.06.24 um 17:22 schrieb Claudio Imbrenda:
> On Fri, 28 Jun 2024 16:53:20 +0200
> Christian Borntraeger <borntraeger@linux.ibm.com> wrote:
> 
>> Am 27.06.24 um 11:57 schrieb Heiko Carstens:
>>> On Thu, Jun 27, 2024 at 11:05:20AM +0200, Christian Borntraeger wrote:
>>>> in rare cases, e.g. for injecting a machine check we do intercept all
>>>> load PSW instructions via ICTL_LPSW. With facility 193 a new variant
>>>> LPSWEY was added. KVM needs to handle that as well.
>>>>
>>>> Fixes: a3efa8429266 ("KVM: s390: gen_facilities: allow facilities 165, 193, 194 and 196")
>>>> Reported-by: Marc Hartmayer <mhartmay@linux.ibm.com>
>>>> Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
>>>> ---
>>>>    arch/s390/include/asm/kvm_host.h |  1 +
>>>>    arch/s390/kvm/kvm-s390.c         |  1 +
>>>>    arch/s390/kvm/kvm-s390.h         | 16 ++++++++++++++++
>>>>    arch/s390/kvm/priv.c             | 32 ++++++++++++++++++++++++++++++++
>>>>    4 files changed, 50 insertions(+)
>>>
>>> ...
>>>    
>>>> +static inline u64 kvm_s390_get_base_disp_siy(struct kvm_vcpu *vcpu, u8 *ar)
>>>> +{
>>>> +	u32 base1 = vcpu->arch.sie_block->ipb >> 28;
>>>> +	u32 disp1 = ((vcpu->arch.sie_block->ipb & 0x0fff0000) >> 16) +
> 
> long disp1 = ...
> 
>>>> +			((vcpu->arch.sie_block->ipb & 0xff00) << 4);
>>>> +
>>>> +	/* The displacement is a 20bit _SIGNED_ value */
>>>> +	if (disp1 & 0x80000)
>>>> +		disp1+=0xfff00000;
> 
> disp1 = sign_extend64(disp1, 20);

Hmm, right. I was just looking at the return statement, but here it is clearly better.

Will send a v2