[libvirt] [PATCH 4/5] conf: drop hugepage non-anoymous memory requirement

[Marc-André Lureau]

Hi

On Tue, Sep 11, 2018 at 2:56 AM, John Ferlan <jferlan at redhat.com> wrote:
>
> "non-anonymous"
>
> On 09/07/2018 07:32 AM, marcandre.lureau at redhat.com wrote:
>> From: Marc-André Lureau <marcandre.lureau at redhat.com>
>>
>> memfd is able to allocate hugepage anonymous memory.
>>
>> Signed-off-by: Marc-André Lureau <marcandre.lureau at redhat.com>
>> ---
>>  src/conf/domain_conf.c | 7 -------
>>  1 file changed, 7 deletions(-)
>>
>
>> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
>> index 86199623cc..696cf6ef18 100644
>> --- a/src/conf/domain_conf.c
>> +++ b/src/conf/domain_conf.c
>> @@ -6186,13 +6186,6 @@ virDomainDefMemtuneValidate(const virDomainDef *def)
>>          return -1;
>>      }
>>
>> -    if (mem->source == VIR_DOMAIN_MEMORY_SOURCE_ANONYMOUS) {
>> -        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
>> -                       _("hugepages are not allowed with anonymous "
>> -                         "memory source"));
>> -        return -1;
>> -    }
>> -
>
>
> I believe we need to move this check into qemu specific code that would
> then be able to test for QEMU_CAPS_OBJECT_MEMORY_MEMFD_HUGETLB


Would that be what you have in mind?

diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 5329899b13..d152466e28 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -3950,10 +3950,19 @@ qemuDomainDefValidateFeatures(const virDomainDef *def,


 static int
-qemuDomainDefValidateMemory(const virDomainDef *def)
+qemuDomainDefValidateMemory(const virDomainDef *def,
+                            virQEMUCapsPtr qemuCaps)
 {
     const long system_page_size = virGetSystemPageSizeKB();

+    if (def->mem.nhugepages != 0 &&
+        def->mem.source == VIR_DOMAIN_MEMORY_SOURCE_ANONYMOUS &&
+        !virQEMUCapsGet(qemuCaps, QEMU_CAPS_OBJECT_MEMORY_MEMFD_HUGETLB)) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                       _("anonymous memory source with hugepages is
not supported"));
+        return -1;
+    }
+
     /* We can't guarantee any other mem.access
      * if no guest NUMA nodes are defined. */
     if (def->mem.nhugepages != 0 &&
@@ -4094,7 +4103,7 @@ qemuDomainDefValidate(const virDomainDef *def,
     if (qemuDomainDefValidateFeatures(def, qemuCaps) < 0)
         goto cleanup;

-    if (qemuDomainDefValidateMemory(def) < 0)
+    if (qemuDomainDefValidateMemory(def, qemuCaps) < 0)
         goto cleanup;

     ret = 0;

> See qemuDomainDefValidateMemory and go from there. I think this may
> require 2 patches though... One to move the two checks that I don't
> think are "mem" specific and the next to add the "filter" that if the
> capability exists, then we can support; otherwise, still fail.
>
> "Theoretically speaking" those are qemu specific checks - the nodemask
> checks done after this would appear to be more generic.
>
> John
>
>
>>      for (i = 0; i < mem->nhugepages; i++) {
>>          size_t j;
>>          ssize_t nextBit;
>>