* [PATCH v2] tools/libs/light: update xenstore entry when setting max domain memory
@ 2022-04-20 8:04 Juergen Gross
2022-04-29 14:52 ` Anthony PERARD
0 siblings, 1 reply; 3+ messages in thread
From: Juergen Gross @ 2022-04-20 8:04 UTC (permalink / raw)
To: xen-devel; +Cc: Juergen Gross, Wei Liu, Anthony PERARD
libxl_domain_setmaxmem() called during "xl mem-max" should update the
domain's memory/static-max Xenstore node, as otherwise "xl mem-set"
won't be able to set the memory size to the new maximum.
Adjust the related comments and documentation accordingly.
Signed-off-by: Juergen Gross <jgross@suse.com>
---
V2:
- adjust comments and docs (Anthony Perard)
---
tools/libs/light/libxl_mem.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/tools/libs/light/libxl_mem.c b/tools/libs/light/libxl_mem.c
index c739d00f39..92ec09f4cf 100644
--- a/tools/libs/light/libxl_mem.c
+++ b/tools/libs/light/libxl_mem.c
@@ -20,8 +20,7 @@
/*
* Set the maximum memory size of the domain in the hypervisor. There is no
* change of the current memory size involved. The specified memory size can
- * even be above the configured maxmem size of the domain, but the related
- * Xenstore entry memory/static-max isn't modified!
+ * even be above the configured maxmem size of the domain.
*/
int libxl_domain_setmaxmem(libxl_ctx *ctx, uint32_t domid, uint64_t max_memkb)
{
@@ -82,6 +81,15 @@ int libxl_domain_setmaxmem(libxl_ctx *ctx, uint32_t domid, uint64_t max_memkb)
goto out;
}
+ rc = libxl__xs_printf(gc, XBT_NULL,
+ GCSPRINTF("%s/memory/static-max", dompath),
+ "%"PRIu64, max_memkb);
+ if (rc != 0) {
+ LOGED(ERROR, domid, "Couldn't set %s/memory/static-max, rc=%d\n",
+ dompath, rc);
+ goto out;
+ }
+
rc = 0;
out:
libxl_domain_config_dispose(&d_config);
--
2.34.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v2] tools/libs/light: update xenstore entry when setting max domain memory
2022-04-20 8:04 [PATCH v2] tools/libs/light: update xenstore entry when setting max domain memory Juergen Gross
@ 2022-04-29 14:52 ` Anthony PERARD
2022-05-02 8:16 ` Juergen Gross
0 siblings, 1 reply; 3+ messages in thread
From: Anthony PERARD @ 2022-04-29 14:52 UTC (permalink / raw)
To: Juergen Gross; +Cc: xen-devel, Wei Liu
On Wed, Apr 20, 2022 at 10:04:26AM +0200, Juergen Gross wrote:
> libxl_domain_setmaxmem() called during "xl mem-max" should update the
> domain's memory/static-max Xenstore node, as otherwise "xl mem-set"
> won't be able to set the memory size to the new maximum.
Setting domain's memory higher than the original mem-max only works on
PV and maybe PVH guest, right? Because on HVM, QEMU is told about
maxmem when starting a guest, and allocates some stuff from this address
(vga buffer, pci rom I think) so trying to give HVM guest more memory
after the fact is probably not going to go smoothly.
> Adjust the related comments and documentation accordingly.
>
> Signed-off-by: Juergen Gross <jgross@suse.com>
> ---
> V2:
> - adjust comments and docs (Anthony Perard)
Maybe `man xl` should be updated as well. In the section about `xl
mem-max`, there is:
"Note however that the initial maxmem value is still used as an
upper limit for xl mem-set. Also note that calling xl mem-set will
reset this value."
That wouldn't be true anymore with this patch.
Thanks,
--
Anthony PERARD
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v2] tools/libs/light: update xenstore entry when setting max domain memory
2022-04-29 14:52 ` Anthony PERARD
@ 2022-05-02 8:16 ` Juergen Gross
0 siblings, 0 replies; 3+ messages in thread
From: Juergen Gross @ 2022-05-02 8:16 UTC (permalink / raw)
To: Anthony PERARD; +Cc: xen-devel, Wei Liu
[-- Attachment #1.1.1: Type: text/plain, Size: 1479 bytes --]
On 29.04.22 16:52, Anthony PERARD wrote:
> On Wed, Apr 20, 2022 at 10:04:26AM +0200, Juergen Gross wrote:
>> libxl_domain_setmaxmem() called during "xl mem-max" should update the
>> domain's memory/static-max Xenstore node, as otherwise "xl mem-set"
>> won't be able to set the memory size to the new maximum.
>
> Setting domain's memory higher than the original mem-max only works on
> PV and maybe PVH guest, right? Because on HVM, QEMU is told about
> maxmem when starting a guest, and allocates some stuff from this address
> (vga buffer, pci rom I think) so trying to give HVM guest more memory
> after the fact is probably not going to go smoothly.
Works without a problem.
This area is marked in the e820 memory map, so the guest won't use it to
add memory.
>
>> Adjust the related comments and documentation accordingly.
>>
>> Signed-off-by: Juergen Gross <jgross@suse.com>
>> ---
>> V2:
>> - adjust comments and docs (Anthony Perard)
>
> Maybe `man xl` should be updated as well. In the section about `xl
> mem-max`, there is:
> "Note however that the initial maxmem value is still used as an
> upper limit for xl mem-set. Also note that calling xl mem-set will
> reset this value."
>
> That wouldn't be true anymore with this patch.
Weird. I did modify that man page, but obviously didn't check it was
really added to the patch. Sorry for that, will resend the patch with
that change included.
Juergen
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^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2022-05-02 8:17 UTC | newest]
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2022-04-20 8:04 [PATCH v2] tools/libs/light: update xenstore entry when setting max domain memory Juergen Gross
2022-04-29 14:52 ` Anthony PERARD
2022-05-02 8:16 ` Juergen Gross
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