Re: [PATCH 5/6] x86/vmx: Defer vmx_vmcs_exit() as long as possible in construct_vmcs()

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 06/06/18 10:45, Roger Pau Monné wrote:
> On Mon, May 28, 2018 at 03:27:57PM +0100, Andrew Cooper wrote:
>> paging_update_paging_modes() and vmx_vlapic_msr_changed() both operate on the
>> VMCS being constructed.  Avoid dropping and re-acquiring the reference
>> multiple times.
>>
>> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
>> ---
>> CC: Jan Beulich <JBeulich@suse.com>
>> CC: Jun Nakajima <jun.nakajima@intel.com>
>> CC: Kevin Tian <kevin.tian@intel.com>
>> CC: Wei Liu <wei.liu2@citrix.com>
>> CC: Roger Pau Monné <roger.pau@citrix.com>
>> ---
>>  xen/arch/x86/hvm/vmx/vmcs.c | 10 ++++++----
>>  1 file changed, 6 insertions(+), 4 deletions(-)
>>
>> diff --git a/xen/arch/x86/hvm/vmx/vmcs.c b/xen/arch/x86/hvm/vmx/vmcs.c
>> index be02be1..ce78f19 100644
>> --- a/xen/arch/x86/hvm/vmx/vmcs.c
>> +++ b/xen/arch/x86/hvm/vmx/vmcs.c
>> @@ -996,6 +996,7 @@ static int construct_vmcs(struct vcpu *v)
>>      struct domain *d = v->domain;
>>      u32 vmexit_ctl = vmx_vmexit_control;
>>      u32 vmentry_ctl = vmx_vmentry_control;
>> +    int rc;
>>  
>>      vmx_vmcs_enter(v);
>>  
>> @@ -1083,8 +1084,8 @@ static int construct_vmcs(struct vcpu *v)
>>  
>>          if ( msr_bitmap == NULL )
>>          {
>> -            vmx_vmcs_exit(v);
>> -            return -ENOMEM;
>> +            rc = -ENOMEM;
>> +            goto out;
>>          }
>>  
>>          memset(msr_bitmap, ~0, PAGE_SIZE);
>> @@ -1258,13 +1259,14 @@ static int construct_vmcs(struct vcpu *v)
>>      if ( cpu_has_vmx_tsc_scaling )
>>          __vmwrite(TSC_MULTIPLIER, d->arch.hvm_domain.tsc_scaling_ratio);
>>  
>> -    vmx_vmcs_exit(v);
>> -
>>      /* will update HOST & GUEST_CR3 as reqd */
>>      paging_update_paging_modes(v);
>>  
>>      vmx_vlapic_msr_changed(v);
>>  
>> + out:
>> +    vmx_vmcs_exit(v);
>> +
>>      return 0;
> Shouldn't you return rc here? Or else you lose the error value.

Yeah - Coverity told me the same...  Fixed up.

~Andrew

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel