Re: [PATCH v2 1/3] x86/svm: Drop the _enabled suffix from vmcb bits

[Jan Beulich <jbeulich@xxxxxxxx>]

On 12.03.2024 11:00, Vaishali Thakkar wrote:
> On 3/12/24 08:54, Jan Beulich wrote:
>> On 11.03.2024 13:40, Vaishali Thakkar wrote:
>>> --- a/xen/arch/x86/hvm/svm/nestedsvm.c
>>> +++ b/xen/arch/x86/hvm/svm/nestedsvm.c
>>> @@ -571,7 +571,7 @@ static int nsvm_vmcb_prepare4vmrun(struct vcpu *v, 
>>> struct cpu_user_regs *regs)
>>>       if ( nestedhvm_paging_mode_hap(v) )
>>>       {
>>>           /* host nested paging + guest nested paging. */
>>> -        n2vmcb->_np_enable = 1;
>>> +        n2vmcb->_np = true;
>>>   
>>>           nestedsvm_vmcb_set_nestedp2m(v, ns_vmcb, n2vmcb);
>>>   
>>> @@ -585,7 +585,7 @@ static int nsvm_vmcb_prepare4vmrun(struct vcpu *v, 
>>> struct cpu_user_regs *regs)
>>>       else if ( paging_mode_hap(v->domain) )
>>>       {
>>>           /* host nested paging + guest shadow paging. */
>>> -        n2vmcb->_np_enable = 1;
>>> +        n2vmcb->_np = true;
>>>           /* Keep h_cr3 as it is. */
>>>           n2vmcb->_h_cr3 = n1vmcb->_h_cr3;
>>>           /* When l1 guest does shadow paging
>>> @@ -601,7 +601,7 @@ static int nsvm_vmcb_prepare4vmrun(struct vcpu *v, 
>>> struct cpu_user_regs *regs)
>>>       else
>>>       {
>>>           /* host shadow paging + guest shadow paging. */
>>> -        n2vmcb->_np_enable = 0;
>>> +        n2vmcb->_np = false;
>>>           n2vmcb->_h_cr3 = 0x0;
>>>   
>>>           /* TODO: Once shadow-shadow paging is in place come back to here
>>> @@ -706,7 +706,7 @@ nsvm_vcpu_vmentry(struct vcpu *v, struct cpu_user_regs 
>>> *regs,
>>>       }
>>>   
>>>       /* nested paging for the guest */
>>> -    svm->ns_hap_enabled = !!ns_vmcb->_np_enable;
>>> +    svm->ns_hap_enabled = ns_vmcb->_np;
>>>   
>>>       /* Remember the V_INTR_MASK in hostflags */
>>>       svm->ns_hostflags.fields.vintrmask = 
>>> !!ns_vmcb->_vintr.fields.intr_masking;
>>> @@ -1084,7 +1084,7 @@ nsvm_vmcb_prepare4vmexit(struct vcpu *v, struct 
>>> cpu_user_regs *regs)
>>>       if ( nestedhvm_paging_mode_hap(v) )
>>>       {
>>>           /* host nested paging + guest nested paging. */
>>> -        ns_vmcb->_np_enable = n2vmcb->_np_enable;
>>> +        ns_vmcb->_np = n2vmcb->_np;
>>>           ns_vmcb->_cr3 = n2vmcb->_cr3;
>>>           /* The vmcb->h_cr3 is the shadowed h_cr3. The original
>>>            * unshadowed guest h_cr3 is kept in ns_vmcb->h_cr3,
>>> @@ -1093,7 +1093,7 @@ nsvm_vmcb_prepare4vmexit(struct vcpu *v, struct 
>>> cpu_user_regs *regs)
>>>       else if ( paging_mode_hap(v->domain) )
>>>       {
>>>           /* host nested paging + guest shadow paging. */
>>> -        ns_vmcb->_np_enable = 0;
>>> +        ns_vmcb->_np = false;
>>>           /* Throw h_cr3 away. Guest is not allowed to set it or
>>>            * it can break out, otherwise (security hole!) */
>>>           ns_vmcb->_h_cr3 = 0x0;
>>> @@ -1104,7 +1104,7 @@ nsvm_vmcb_prepare4vmexit(struct vcpu *v, struct 
>>> cpu_user_regs *regs)
>>>       else
>>>       {
>>>           /* host shadow paging + guest shadow paging. */
>>> -        ns_vmcb->_np_enable = 0;
>>> +        ns_vmcb->_np = false;
>>>           ns_vmcb->_h_cr3 = 0x0;
>>>           /* The vmcb->_cr3 is the shadowed cr3. The original
>>>            * unshadowed guest cr3 is kept in ns_vmcb->_cr3,
>>
>> While spotting the small issue below it occurred to me: Why is it that
>> vmcb_set_...() is open-coded everywhere here? I think this would be
>> pretty nice to avoid at the same time (for lines touched anyway, or in
>> a separate prereq patch, or alternatively [and only ideally] for all
>> other instances in a follow-on patch). Thoughts?
> 
> Yes, I noticed this too. My plan was to send a followup patch for
> fixing all the instances where vmcb_set/get_...() can be used.
> There are bunch of other vmcb bits (apart from the ones being
> handled in this patchset) in this file and in svm.c which can
> benefit from using VMCB accessors.

To keep churn as well as effort to find commits touching individual lines
low, doing the conversion when touching lines anyway is imo preferable. A
follow-on patch can then convert what's left.

Jan