External/libvirt
1
0
Fork 0
mirror of https://gitlab.com/libvirt/libvirt.git synced 2025-03-20 07:59:00 +00:00
Code

domain: fix parsing of memory tunables on 32-bit machines

Browse Source 
Commit 6c9a8a4 (Oct 2014) exposed a long-standing issue on 32-bit
machines: code related to virDomainSetMemoryParameters has always
been documented as using a 64-bit limit, but it was implemented by
calling virDomainParseMemory which enforced an 'unsigned long'
limit.  Since VIR_DOMAIN_MEMORY_PARAM_UNLIMITED capped to a
long is -1, but virDomainParseScaledValue no longer accepts
negative values, an attempt to use 2^53-1 as a hard memory limit
started failing the testsuite.  However, the problem with capping
things artificially low has existed for much longer - ever since
commits 4888f0fb and 2e22f23 (Mar 2012) switched internal tracking
from 'unsigned long' to 'unsigned long long' (prior to that time,
the cap was a side-effect of the choice of types).  We _have_ to
cap the balloon memory values, (no thanks to baked in 'unsigned long'
of API such as virDomainSetMaxMemory or virDomainGetInfo with no
counterpart API that guarantees 64-bit access to those numbers)
but memory parameters have never needed the artificial limit.

At any rate, the solution is to make the parser function gain a
parameter, and only do the reduced 32-bit cap for the values that
are constrained due to API.

* src/conf/domain_conf.h (_virDomainMemtune): Add comments.
* src/conf/domain_conf.c (virDomainParseMemory): Add parameter.
(virDomainDefParseXML): Adjust callers.

Signed-off-by: Eric Blake <eblake@redhat.com>
This commit is contained in:
Eric Blake 2014-10-30 13:42:44 -06:00
parent be598c5ff8
commit 9998a657fd
2 changed files with 22 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
src/conf/domain_conf.c
View File

@ -6380,19 +6380,23 @@ virDomainParseScaledValue(const char *xpath,
/* Parse a memory element located at XPATH within CTXT, and store the
* result into MEM. If REQUIRED, then the value must exist;
* otherwise, the value is optional. The value is in blocks of 1024.
* result into MEM, in blocks of 1024. If REQUIRED, then the value
* must exist; otherwise, the value is optional. The value must not
* exceed VIR_DOMAIN_MEMORY_PARAM_UNLIMITED once scaled; additionally,
* if CAPPED is true, the value must fit within an unsigned long (only
* matters on 32-bit platforms).
*
* Return 0 on success, -1 on failure after issuing error. */
static int
virDomainParseMemory(const char *xpath, xmlXPathContextPtr ctxt,
unsigned long long *mem, bool required)
unsigned long long *mem, bool required, bool capped)
{
int ret = -1;
unsigned long long bytes, max;
/* On 32-bit machines, our bound is 0xffffffff * KiB. On 64-bit
* machines, our bound is off_t (2^63). */
if (sizeof(unsigned long) < sizeof(long long))
if (capped && sizeof(unsigned long) < sizeof(long long))
max = 1024ull * ULONG_MAX;
else
max = LLONG_MAX;
@ -12222,11 +12226,11 @@ virDomainDefParseXML(xmlDocPtr xml,
/* Extract domain memory */
if (virDomainParseMemory("./memory[1]", ctxt,
&def->mem.max_balloon, true) < 0)
&def->mem.max_balloon, true, true) < 0)
goto error;
if (virDomainParseMemory("./currentMemory[1]", ctxt,
&def->mem.cur_balloon, false) < 0)
&def->mem.cur_balloon, false, true) < 0)
goto error;
/* and info about it */
@ -12346,19 +12350,19 @@ virDomainDefParseXML(xmlDocPtr xml,
/* Extract other memory tunables */
if (virDomainParseMemory("./memtune/hard_limit[1]", ctxt,
&def->mem.hard_limit, false) < 0)
&def->mem.hard_limit, false, false) < 0)
goto error;
if (virDomainParseMemory("./memtune/soft_limit[1]", ctxt,
&def->mem.soft_limit, false) < 0)
&def->mem.soft_limit, false, false) < 0)
goto error;
if (virDomainParseMemory("./memtune/min_guarantee[1]", ctxt,
&def->mem.min_guarantee, false) < 0)
&def->mem.min_guarantee, false, false) < 0)
goto error;
if (virDomainParseMemory("./memtune/swap_hard_limit[1]", ctxt,
&def->mem.swap_hard_limit, false) < 0)
&def->mem.swap_hard_limit, false, false) < 0)
goto error;
n = virXPathULong("string(./vcpu[1])", ctxt, &count);

14
src/conf/domain_conf.h
View File

@ -1966,8 +1966,10 @@ typedef struct _virDomainMemtune virDomainMemtune;
typedef virDomainMemtune *virDomainMemtunePtr;
struct _virDomainMemtune {
unsigned long long max_balloon; /* in kibibytes */
unsigned long long cur_balloon; /* in kibibytes */
unsigned long long max_balloon; /* in kibibytes, capped at ulong thanks
to virDomainGetMaxMemory */
unsigned long long cur_balloon; /* in kibibytes, capped at ulong thanks
to virDomainGetInfo */
virDomainHugePagePtr hugepages;
size_t nhugepages;
@ -1975,10 +1977,10 @@ struct _virDomainMemtune {
bool nosharepages;
bool locked;
int dump_core; /* enum virTristateSwitch */
unsigned long long hard_limit; /* in kibibytes */
unsigned long long soft_limit; /* in kibibytes */
unsigned long long min_guarantee; /* in kibibytes */
unsigned long long swap_hard_limit; /* in kibibytes */
unsigned long long hard_limit; /* in kibibytes, limit at off_t bytes */
unsigned long long soft_limit; /* in kibibytes, limit at off_t bytes */
unsigned long long min_guarantee; /* in kibibytes, limit at off_t bytes */
unsigned long long swap_hard_limit; /* in kibibytes, limit at off_t bytes */
};
typedef struct _virDomainPowerManagement virDomainPowerManagement;