Re: [Xen-devel] [PATCH V2 1/2] x86/altp2m: Add hypercall to set a range of sve bits

[Alexandru Stefan ISAILA <aisaila@bitdefender.com>]

On 06.11.2019 23:06, Tamas K Lengyel wrote:
> On Wed, Nov 6, 2019 at 7:35 AM Alexandru Stefan ISAILA
> <aisaila@bitdefender.com> wrote:
>>
>> By default the sve bits are not set.
>> This patch adds a new hypercall, xc_altp2m_set_supress_ve_multi(),
>> to set a range of sve bits.
>> The core function, p2m_set_suppress_ve_multi(), does not brake in case
>> of a error and it is doing a best effort for setting the bits in the
>> given range. A check for continuation is made in order to have
>> preemption on big ranges.
>>
>> Signed-off-by: Alexandru Isaila <aisaila@bitdefender.com>
>>
>> ---
>> Changes since V1:
>>          - Remove "continue"
>>          - Add a new field in xen_hvm_altp2m_suppress_ve to store the
>> continuation value
>>          - Have p2m_set_suppress_ve_multi() take
>> xen_hvm_altp2m_suppress_ve as a param.
>> ---
>>   tools/libxc/include/xenctrl.h   |  3 ++
>>   tools/libxc/xc_altp2m.c         | 25 ++++++++++++++
>>   xen/arch/x86/hvm/hvm.c          | 20 ++++++++++--
>>   xen/arch/x86/mm/p2m.c           | 58 +++++++++++++++++++++++++++++++++
>>   xen/include/public/hvm/hvm_op.h |  5 ++-
>>   xen/include/xen/mem_access.h    |  3 ++
>>   6 files changed, 111 insertions(+), 3 deletions(-)
>>
>> diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h
>> index f4431687b3..21b644f459 100644
>> --- a/tools/libxc/include/xenctrl.h
>> +++ b/tools/libxc/include/xenctrl.h
>> @@ -1923,6 +1923,9 @@ int xc_altp2m_switch_to_view(xc_interface *handle, uint32_t domid,
>>                                uint16_t view_id);
>>   int xc_altp2m_set_suppress_ve(xc_interface *handle, uint32_t domid,
>>                                 uint16_t view_id, xen_pfn_t gfn, bool sve);
>> +int xc_altp2m_set_supress_ve_multi(xc_interface *handle, uint32_t domid,
>> +                                   uint16_t view_id, xen_pfn_t start_gfn,
>> +                                   uint32_t nr, bool sve);
>>   int xc_altp2m_get_suppress_ve(xc_interface *handle, uint32_t domid,
>>                                 uint16_t view_id, xen_pfn_t gfn, bool *sve);
>>   int xc_altp2m_set_mem_access(xc_interface *handle, uint32_t domid,
>> diff --git a/tools/libxc/xc_altp2m.c b/tools/libxc/xc_altp2m.c
>> index 09dad0355e..6605d9abbe 100644
>> --- a/tools/libxc/xc_altp2m.c
>> +++ b/tools/libxc/xc_altp2m.c
>> @@ -234,6 +234,31 @@ int xc_altp2m_set_suppress_ve(xc_interface *handle, uint32_t domid,
>>       return rc;
>>   }
>>
>> +int xc_altp2m_set_supress_ve_multi(xc_interface *handle, uint32_t domid,
>> +                                   uint16_t view_id, xen_pfn_t start_gfn,
>> +                                   uint32_t nr, bool sve)
>> +{
>> +    int rc;
>> +    DECLARE_HYPERCALL_BUFFER(xen_hvm_altp2m_op_t, arg);
>> +
>> +    arg = xc_hypercall_buffer_alloc(handle, arg, sizeof(*arg));
> 
> Does xc_hypercall_buffer_alloc null-initialize the structure?
> 

It calls xencall_alloc_buffer_pages() which calls memset(p, 0, nr_pages 
* PAGE_SIZE) before returning.

Alex
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