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Re: [XEN PATCH v2 5/5] x86/amd: optional build of amd.c


  • To: Sergiy Kibrik <sergiy_kibrik@xxxxxxxx>
  • From: Jan Beulich <jbeulich@xxxxxxxx>
  • Date: Thu, 29 Aug 2024 12:02:54 +0200
  • Autocrypt: addr=jbeulich@xxxxxxxx; keydata= xsDiBFk3nEQRBADAEaSw6zC/EJkiwGPXbWtPxl2xCdSoeepS07jW8UgcHNurfHvUzogEq5xk hu507c3BarVjyWCJOylMNR98Yd8VqD9UfmX0Hb8/BrA+Hl6/DB/eqGptrf4BSRwcZQM32aZK 7Pj2XbGWIUrZrd70x1eAP9QE3P79Y2oLrsCgbZJfEwCgvz9JjGmQqQkRiTVzlZVCJYcyGGsD /0tbFCzD2h20ahe8rC1gbb3K3qk+LpBtvjBu1RY9drYk0NymiGbJWZgab6t1jM7sk2vuf0Py O9Hf9XBmK0uE9IgMaiCpc32XV9oASz6UJebwkX+zF2jG5I1BfnO9g7KlotcA/v5ClMjgo6Gl MDY4HxoSRu3i1cqqSDtVlt+AOVBJBACrZcnHAUSuCXBPy0jOlBhxPqRWv6ND4c9PH1xjQ3NP nxJuMBS8rnNg22uyfAgmBKNLpLgAGVRMZGaGoJObGf72s6TeIqKJo/LtggAS9qAUiuKVnygo 3wjfkS9A3DRO+SpU7JqWdsveeIQyeyEJ/8PTowmSQLakF+3fote9ybzd880fSmFuIEJldWxp Y2ggPGpiZXVsaWNoQHN1c2UuY29tPsJgBBMRAgAgBQJZN5xEAhsDBgsJCAcDAgQVAggDBBYC AwECHgECF4AACgkQoDSui/t3IH4J+wCfQ5jHdEjCRHj23O/5ttg9r9OIruwAn3103WUITZee e7Sbg12UgcQ5lv7SzsFNBFk3nEQQCACCuTjCjFOUdi5Nm244F+78kLghRcin/awv+IrTcIWF hUpSs1Y91iQQ7KItirz5uwCPlwejSJDQJLIS+QtJHaXDXeV6NI0Uef1hP20+y8qydDiVkv6l IreXjTb7DvksRgJNvCkWtYnlS3mYvQ9NzS9PhyALWbXnH6sIJd2O9lKS1Mrfq+y0IXCP10eS FFGg+Av3IQeFatkJAyju0PPthyTqxSI4lZYuJVPknzgaeuJv/2NccrPvmeDg6Coe7ZIeQ8Yj t0ARxu2xytAkkLCel1Lz1WLmwLstV30g80nkgZf/wr+/BXJW/oIvRlonUkxv+IbBM3dX2OV8 AmRv1ySWPTP7AAMFB/9PQK/VtlNUJvg8GXj9ootzrteGfVZVVT4XBJkfwBcpC/XcPzldjv+3 HYudvpdNK3lLujXeA5fLOH+Z/G9WBc5pFVSMocI71I8bT8lIAzreg0WvkWg5V2WZsUMlnDL9 mpwIGFhlbM3gfDMs7MPMu8YQRFVdUvtSpaAs8OFfGQ0ia3LGZcjA6Ik2+xcqscEJzNH+qh8V m5jjp28yZgaqTaRbg3M/+MTbMpicpZuqF4rnB0AQD12/3BNWDR6bmh+EkYSMcEIpQmBM51qM EKYTQGybRCjpnKHGOxG0rfFY1085mBDZCH5Kx0cl0HVJuQKC+dV2ZY5AqjcKwAxpE75MLFkr wkkEGBECAAkFAlk3nEQCGwwACgkQoDSui/t3IH7nnwCfcJWUDUFKdCsBH/E5d+0ZnMQi+G0A nAuWpQkjM1ASeQwSHEeAWPgskBQL
  • Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
  • Delivery-date: Thu, 29 Aug 2024 10:03:05 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

On 29.08.2024 11:48, Sergiy Kibrik wrote:
> 19.08.24 15:36, Jan Beulich:
>> On 16.08.2024 13:19, Sergiy Kibrik wrote:
>>> --- a/xen/arch/x86/hvm/svm/svm.c
>>> +++ b/xen/arch/x86/hvm/svm/svm.c
>>> @@ -919,7 +919,8 @@ static void cf_check svm_ctxt_switch_from(struct vcpu 
>>> *v)
>>>        * Possibly clear previous guest selection of SSBD if set.  Note that
>>>        * SPEC_CTRL.SSBD is already handled by svm_vmexit_spec_ctrl.
>>>        */
>>> -    if ( v->arch.msrs->virt_spec_ctrl.raw & SPEC_CTRL_SSBD )
>>> +    if ( IS_ENABLED(CONFIG_AMD) &&
>>> +         v->arch.msrs->virt_spec_ctrl.raw & SPEC_CTRL_SSBD )
>>>       {
>>>           ASSERT(v->domain->arch.cpuid->extd.virt_ssbd);
>>>           amd_set_legacy_ssbd(false);
>>> @@ -953,7 +954,8 @@ static void cf_check svm_ctxt_switch_to(struct vcpu *v)
>>>           wrmsr_tsc_aux(v->arch.msrs->tsc_aux);
>>>   
>>>       /* Load SSBD if set by the guest. */
>>> -    if ( v->arch.msrs->virt_spec_ctrl.raw & SPEC_CTRL_SSBD )
>>> +    if ( IS_ENABLED(CONFIG_AMD) &&
>>> +         v->arch.msrs->virt_spec_ctrl.raw & SPEC_CTRL_SSBD )
>>>       {
>>>           ASSERT(v->domain->arch.cpuid->extd.virt_ssbd);
>>>           amd_set_legacy_ssbd(true);
>> Instead of these changes, shouldn't AMD_SVM become dependent upon AMD in
>> Kconfig?
> 
> It could be done earlier, yet I haven't done so since we briefly touched 
> this before and decided not to link {AMD,INTEL} with {AMD_SVM,INTEL_VMX} 
> then:
> 
> https://lore.kernel.org/xen-devel/9a973f18-e0af-456c-8b07-6869f044519e@xxxxxxxxxx/

Yet that only suggests that e.g HYGON also ought to select AMD_SVM. Which
will happen transitively with HYGON selecting AMD (in the earlier patch).

Jan



 


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