Re: [Xen-devel] [PATCH 03/11] x86/HVM: Hardware alternate p2m support detection.

[Ed White <edmund.h.white@xxxxxxxxx>]

On 01/12/2015 09:08 AM, Andrew Cooper wrote:
> On 09/01/15 21:26, Ed White wrote:
>> As implemented here, only supported on platforms with VMX HAP.
>>
>> Signed-off-by: Ed White <edmund.h.white@xxxxxxxxx>
>> ---
>>  xen/arch/x86/hvm/hvm.c        | 8 ++++++++
>>  xen/arch/x86/hvm/vmx/vmx.c    | 1 +
>>  xen/include/asm-x86/hvm/hvm.h | 6 ++++++
>>  3 files changed, 15 insertions(+)
>>
>> diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
>> index bc414ff..3a7367c 100644
>> --- a/xen/arch/x86/hvm/hvm.c
>> +++ b/xen/arch/x86/hvm/hvm.c
>> @@ -157,6 +157,9 @@ static int __init hvm_enable(void)
>>      if ( !fns->pvh_supported )
>>          printk(XENLOG_INFO "HVM: PVH mode not supported on this 
>> platform\n");
>>  
>> +    if ( !fns->altp2m_supported )
>> +        printk(XENLOG_INFO "HVM: Alternate p2m mode not supported on this 
>> platform\n");
>> +
> 
> I am not sure this message is particularly useful.  The PVH message
> above is just transitory until PVH looses some of its restrictions.
> 
>>      /*
>>       * Allow direct access to the PC debug ports 0x80 and 0xed (they are
>>       * often used for I/O delays, but the vmexits simply slow things down).
>> @@ -6369,6 +6372,11 @@ enum hvm_intblk nhvm_interrupt_blocked(struct vcpu *v)
>>      return hvm_funcs.nhvm_intr_blocked(v);
>>  }
>>  
>> +bool_t hvm_altp2m_supported()
> 
> I have to admit that I am somewhat uneasy about the name "altp2m", but I
> can't suggest anything better at the moment.  I am all ears if anyone
> else has any other suggestions.
> 

Me too. The first name I used was even worse.

Ed

>> +{
>> +    return hvm_funcs.altp2m_supported;
>> +}
>> +
>>  /*
>>   * Local variables:
>>   * mode: C
>> diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
>> index f2554d6..931709b 100644
>> --- a/xen/arch/x86/hvm/vmx/vmx.c
>> +++ b/xen/arch/x86/hvm/vmx/vmx.c
>> @@ -1796,6 +1796,7 @@ const struct hvm_function_table * __init 
>> start_vmx(void)
>>      if ( cpu_has_vmx_ept && (cpu_has_vmx_pat || opt_force_ept) )
>>      {
>>          vmx_function_table.hap_supported = 1;
>> +        vmx_function_table.altp2m_supported = 1;
>>  
>>          vmx_function_table.hap_capabilities = 0;
>>  
>> diff --git a/xen/include/asm-x86/hvm/hvm.h b/xen/include/asm-x86/hvm/hvm.h
>> index e3d2d9a..7115a68 100644
>> --- a/xen/include/asm-x86/hvm/hvm.h
>> +++ b/xen/include/asm-x86/hvm/hvm.h
>> @@ -94,6 +94,9 @@ struct hvm_function_table {
>>      /* Necessary hardware support for PVH mode? */
>>      int pvh_supported;
>>  
>> +    /* Necessary hardware support for alternate p2m's? */
>> +    int altp2m_supported;
> 
> bool_t please.  (The adjacent examples are poor)
> 
> ~Andrew
> 
>> +
>>      /* Indicate HAP capabilities. */
>>      int hap_capabilities;
>>  
>> @@ -518,6 +521,9 @@ bool_t nhvm_vmcx_hap_enabled(struct vcpu *v);
>>  /* interrupt */
>>  enum hvm_intblk nhvm_interrupt_blocked(struct vcpu *v);
>>  
>> +/* returns true if hardware supports alternate p2m's */
>> +bool_t hvm_altp2m_supported(void);
>> +
>>  #ifndef NDEBUG
>>  /* Permit use of the Forced Emulation Prefix in HVM guests */
>>  extern bool_t opt_hvm_fep;
> 
> 

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