Re: [PATCH v3 4/4] x86/svm: Drop emulation of Intel's SYSENTER behaviour on AMD systems

[Alejandro Vallejo <alejandro.garciavallejo@xxxxxxx>]

On Wed Mar 11, 2026 at 9:46 AM CET, Jan Beulich wrote:
> On 13.02.2026 12:42, Alejandro Vallejo wrote:
>> @@ -501,6 +492,9 @@ static void svm_save_cpu_state(struct vcpu *v, struct 
>> hvm_hw_cpu *data)
>>  {
>>      struct vmcb_struct *vmcb = v->arch.hvm.svm.vmcb;
>>  
>> +    data->sysenter_cs      = vmcb->sysenter_cs;
>> +    data->sysenter_esp     = vmcb->sysenter_esp;
>> +    data->sysenter_eip     = vmcb->sysenter_eip;
>>      data->shadow_gs        = vmcb->kerngsbase;
>>      data->msr_lstar        = vmcb->lstar;
>>      data->msr_star         = vmcb->star;
>
> May I suggest to do writes by increasing address order? I.e. while this
> already looks fine, ...
>
>> @@ -512,11 +506,14 @@ static void svm_load_cpu_state(struct vcpu *v, struct 
>> hvm_hw_cpu *data)
>>  {
>>      struct vmcb_struct *vmcb = v->arch.hvm.svm.vmcb;
>>  
>> -    vmcb->kerngsbase = data->shadow_gs;
>> -    vmcb->lstar      = data->msr_lstar;
>> -    vmcb->star       = data->msr_star;
>> -    vmcb->cstar      = data->msr_cstar;
>> -    vmcb->sfmask     = data->msr_syscall_mask;
>> +    vmcb->sysenter_cs  = data->sysenter_cs;
>> +    vmcb->sysenter_esp = data->sysenter_esp;
>> +    vmcb->sysenter_eip = data->sysenter_eip;
>> +    vmcb->kerngsbase   = data->shadow_gs;
>> +    vmcb->lstar        = data->msr_lstar;
>> +    vmcb->star         = data->msr_star;
>> +    vmcb->cstar        = data->msr_cstar;
>> +    vmcb->sfmask       = data->msr_syscall_mask;
>>      v->arch.hvm.guest_efer = data->msr_efer;
>>      svm_update_guest_efer(v);
>>  }
>
> ... your additions would want to move down here (and the other writes may
> then want re-ordering as well). Preferably with that:

Sure.

> Acked-by: Jan Beulich <jbeulich@xxxxxxxx>

Thanks.

Alejandro