Re: [Xen-devel] [PATCH 07/13] libx86: Introduce a helper to serialise msr_{domain, vcpu}_policy objects
>>> On 04.07.18 at 18:56, wrote:
> On 04/07/18 10:16, Jan Beulich wrote:
>>
>>> @@ -325,6 +325,13 @@ typedef struct xen_cpuid_leaf {
>>> } xen_cpuid_leaf_t;
>>> DEFINE_XEN_GUEST_HANDLE(xen_cpuid_leaf_t);
>>>
>>> +typedef struct xen_msr_entry {
>>> +uint32_t idx;
>>> +uint32_t flags; /* Reserved MBZ. */
>> ... it remains unclear in this patch whose responsibility it is to clear this
>> field. I wonder whether copy_msr_to_buffer() should make sure of this.
>
> copy_msr_to_buffer() does explicitly zero this field.
>
>> +const xen_msr_entry_t ent = { .idx = idx, .val = val };
>
> guarantees that the flags field is 0.
Oh, I'm sorry - so it does. I had searched the patch for instances of
"flags" only ...
Jan
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Re: [Xen-devel] [PATCH 07/13] libx86: Introduce a helper to serialise msr_{domain, vcpu}_policy objects
On 04/07/18 10:16, Jan Beulich wrote:
>
>> @@ -325,6 +325,13 @@ typedef struct xen_cpuid_leaf {
>> } xen_cpuid_leaf_t;
>> DEFINE_XEN_GUEST_HANDLE(xen_cpuid_leaf_t);
>>
>> +typedef struct xen_msr_entry {
>> +uint32_t idx;
>> +uint32_t flags; /* Reserved MBZ. */
> ... it remains unclear in this patch whose responsibility it is to clear this
> field. I wonder whether copy_msr_to_buffer() should make sure of this.
copy_msr_to_buffer() does explicitly zero this field.
> +const xen_msr_entry_t ent = { .idx = idx, .val = val };
guarantees that the flags field is 0.
FWIW, an earlier version of this series has an AVAILABLE bit specified
in the flags field, but attempting to the marshalling code work sensibly
is why I eventually decided to write c/s 2df1d2ba132ff "x86/msr: Drop
{MISC_ENABLES,PLATFORM_INFO}.available" as an alternative fix for the
problem.
~Andrew
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Re: [Xen-devel] [PATCH 07/13] libx86: Introduce a helper to serialise msr_{domain, vcpu}_policy objects
>>> On 03.07.18 at 22:55, wrote:
> From: Roger Pau Monné
>
> As with CPUID, the an architectural form is used for representing the MSR
Stray "the".
Apart from that same remark(s) as for the respective CPUID change,
plus ...
> @@ -325,6 +325,13 @@ typedef struct xen_cpuid_leaf {
> } xen_cpuid_leaf_t;
> DEFINE_XEN_GUEST_HANDLE(xen_cpuid_leaf_t);
>
> +typedef struct xen_msr_entry {
> +uint32_t idx;
> +uint32_t flags; /* Reserved MBZ. */
... it remains unclear in this patch whose responsibility it is to clear this
field. I wonder whether copy_msr_to_buffer() should make sure of this.
Jan
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