linux-kernel - Re: [PATCH v1 4/4] KVM: MMU: Expose the LA57 feature to VM.

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Date:   Thu, 17 Aug 2017 16:29:42 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Yu Zhang <yu.c.zhang@...ux.intel.com>, kvm@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, rkrcmar@...hat.com,
        tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
        xiaoguangrong@...cent.com, joro@...tes.org
Subject: Re: [PATCH v1 4/4] KVM: MMU: Expose the LA57 feature to VM.

On 17/08/2017 13:53, Yu Zhang wrote:
> 
> 
> On 8/17/2017 7:57 PM, Paolo Bonzini wrote:
>> On 12/08/2017 15:35, Yu Zhang wrote:
>>> index a98b88a..50107ae 100644
>>> --- a/arch/x86/kvm/emulate.c
>>> +++ b/arch/x86/kvm/emulate.c
>>> @@ -694,7 +694,7 @@ static __always_inline int __linearize(struct
>>> x86_emulate_ctxt *ctxt,
>>>       switch (mode) {
>>>       case X86EMUL_MODE_PROT64:
>>>           *linear = la;
>>> -        if (is_noncanonical_address(la))
>>> +        if (emul_is_noncanonical_address(la, ctxt))
>>>               goto bad;
>>>             *max_size = min_t(u64, ~0u, (1ull << 48) - la);
>> Oops, you missed one here.  Probably best to use ctxt_virt_addr_bits and
>> then "inline" emul_is_noncanonical_address as "get_canonical(la,
>> va_bits) != la".
> 
> Sorry, I just sent out the v2 patch set without noticing this reply. :-)
> 
> The emul_is_noncanonical() is defined in x86.h so that no
> ctxt_virt_addr_bits needed in emulate.c, are you
> suggesting to use ctx_virt_addr_bits in this file each time before
> emul_is_noncanonical_address() is called?

No, only in this instance which uses "48" after the call to
emul_is_noncanonical_address.

Paolo