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Re: [PATCH] target/i386: implement undocumented "smsw r32" behavior
From: |
Paolo Bonzini |
Subject: |
Re: [PATCH] target/i386: implement undocumented "smsw r32" behavior |
Date: |
Thu, 2 Jul 2020 11:49:37 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 |
On 02/07/20 11:37, Roman Bolshakov wrote:
> On Fri, Jun 26, 2020 at 06:44:19AM -0400, Paolo Bonzini wrote:
>> In 32-bit mode, the higher 16 bits of the destination
>> register are undefined. In practice CR0[31:0] is stored,
>> just like in 64-bit mode, so just remove the "if" that
>> currently differentiates the behavior.
>>
>> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
>
> Hi Paolo,
>
> It seems to be a follow-up to the kvm-unit-tests patch:
> https://patchwork.kernel.org/patch/11590445/
It would be if I had seen that patch! O:-) I'll add the Reported-by of
course.
Paolo
> Could you please add:
> Reported-by: Roman Bolshakov <r.bolshakov@yadro.com>
>
>> ---
>> target/i386/translate.c | 13 +++++++------
>> 1 file changed, 7 insertions(+), 6 deletions(-)
>>
>> diff --git a/target/i386/translate.c b/target/i386/translate.c
>> index 4d808a6f93..60eac03498 100644
>> --- a/target/i386/translate.c
>> +++ b/target/i386/translate.c
>> @@ -7579,12 +7579,13 @@ static target_ulong disas_insn(DisasContext *s,
>> CPUState *cpu)
>> CASE_MODRM_OP(4): /* smsw */
>> gen_svm_check_intercept(s, pc_start, SVM_EXIT_READ_CR0);
>> tcg_gen_ld_tl(s->T0, cpu_env, offsetof(CPUX86State, cr[0]));
>> - if (CODE64(s)) {
>> - mod = (modrm >> 6) & 3;
>> - ot = (mod != 3 ? MO_16 : s->dflag);
>> - } else {
>> - ot = MO_16;
>> - }
>> + /*
>> + * In 32-bit mode, the higher 16 bits of the destination
>> + * register are undefined. In practice CR0[31:0] is stored
>> + * just like in 64-bit mode.
>> + */
>> + mod = (modrm >> 6) & 3;
>> + ot = (mod != 3 ? MO_16 : s->dflag);
>> gen_ldst_modrm(env, s, modrm, ot, OR_TMP0, 1);
>> break;
>> case 0xee: /* rdpkru */
>> --
>> 2.26.2
>>
>>
>
> Reviewed-by: Roman Bolshakov <r.bolshakov@yadro.com>
>
> Regards,
> Roman
>