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SubjectRe: [PATCH] KVM: arm64: Fix 64 bit mmio handle
On 2022-06-30 17:50, Schspa Shi wrote:
> Marc Zyngier <maz@kernel.org> writes:
>
>> On Thu, 30 Jun 2022 17:12:20 +0100,
>> Schspa Shi <schspa@gmail.com> wrote:
>>>
>>> If the len is 8 bytes, we can't get the correct sign extend for
>>> be system.
>>
>> I'm afraid you'll have to give me a bit more details.
>>
>>>
>>> Fix the mask type len and the comparison of length.
>>>
>>> Signed-off-by: Schspa Shi <schspa@gmail.com>
>>> ---
>>> arch/arm64/kvm/mmio.c | 4 ++--
>>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/arch/arm64/kvm/mmio.c b/arch/arm64/kvm/mmio.c
>>> index 3dd38a151d2a6..0692f8b18f35c 100644
>>> --- a/arch/arm64/kvm/mmio.c
>>> +++ b/arch/arm64/kvm/mmio.c
>>> @@ -81,8 +81,8 @@ unsigned long kvm_mmio_read_buf(const void *buf,
>>> unsigned int len)
>>> int kvm_handle_mmio_return(struct kvm_vcpu *vcpu)
>>> {
>>> unsigned long data;
>>> + unsigned long mask;
>>> unsigned int len;
>>> - int mask;
>>> /* Detect an already handled MMIO return */
>>> if (unlikely(!vcpu->mmio_needed))
>>> @@ -97,7 +97,7 @@ int kvm_handle_mmio_return(struct kvm_vcpu *vcpu)
>>> data = kvm_mmio_read_buf(run->mmio.data, len);
>>> if (kvm_vcpu_dabt_issext(vcpu) &&
>>> - len < sizeof(unsigned long)) {
>>> + len <= sizeof(unsigned long)) {
>>
>> If you're reading an 8 byte quantity, what is there to sign-extend?
>> Sign extension only makes sense if what you're reading is *smaller*
>> than the size of the register you are targeting.
>>
>
> Yes, you are correct, sorry for my bad patch.
> Please ignore this patch.
>
>> I must be missing something. And how is that related to running BE? BE
>> in the host? The guest?
>
> I mean BE is for guest running with BE mode.

So what problem did you see? If you have noticed something going
wrong, I'd like to get it fixed.

Thanks,

M.
--
Jazz is not dead. It just smells funny...

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