| Message ID | 20220420080426.7036-1-jgross@suse.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v2] tools/libs/light: update xenstore entry when setting max domain memory | expand |
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,
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
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);
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(-)