On Fri, Oct 02, 2020 at 11:31:32AM -0400, Masayoshi Mizuma wrote:
> Hello Jan, and Michal,
>
> commit: 88957116c9 ("qemu: Use memory-backend-* for regular guest memory") gets
> the system memory sharable without numa config.
> The qemu options with the patch will be like as:
>
> -machine pc-q35-5.2,accel=kvm,usb=off,vmport=off,smm=on,dump-guest-core=off,memory-backend=pc.ram \
> -object memory-backend-file,id=pc.ram,mem-path=/var/lib/libvirt/qemu/ram/2-Test/pc.ram,share=yes,size=17179869184 \
>
> So, we can remove the numa restriction of virtiofs, right?
> The patch to remove that is the bottom of this email.
>
> And, 88957116c9 seems to introduce another restriction which we
> cannot create numa nodes on the machine. I got the following
> message when I set the numa config and started the VM:
>
> 2020-10-02T00:31:46.780374Z qemu-system-x86_64: '-machine memory-backend' and '-numa memdev' properties are mutually exclusive
It seems that this isn't a restriction for virtiofs. It's a bug introduced
by commit: 88957116c9. <numa> element doesn't work regardless of virtiofs config...
- Masa
>
> qemu rejects the -machine memory-backend' and '-numa memdev' because it
> may cause crash. commit: ea81f98bce ("numa: prevent usage of -M memory-backend
> and -numa memdev at the same time") introduced the check.
>
> Do you have any ideas to solve above?
>
> ===================================================================
> From: Masayoshi Mizuma <m.mizuma@xxxxxxxxxxxxxx>
> Date: Fri, 2 Oct 2020 10:50:06 -0400
> Subject: [PATCH] qemu: Remove the number of numa restriction for virtiofs
>
> virtiofs requires at least one numa node to access the system
> memory as shared memory.
>
> 88957116c9 ("qemu: Use memory-backend-* for regular guest memory")
> gets the system memory sharable without the numa config.
>
> Let's remove the number of numa restriction for virtiofs.
>
> Signed-off-by: Masayoshi Mizuma <m.mizuma@xxxxxxxxxxxxxx>
> ---
> src/qemu/qemu_validate.c | 44 ++++++++++++++++++++--------------------
> 1 file changed, 22 insertions(+), 22 deletions(-)
>
> diff --git a/src/qemu/qemu_validate.c b/src/qemu/qemu_validate.c
> index a212605579..b5372e7499 100644
> --- a/src/qemu/qemu_validate.c
> +++ b/src/qemu/qemu_validate.c
> @@ -3475,36 +3475,36 @@ qemuValidateDomainDefVirtioFSSharedMemory(const virDomainDef *def)
> size_t numa_nodes = virDomainNumaGetNodeCount(def->numa);
> size_t i;
>
> - if (numa_nodes == 0) {
> + if ((!numa_nodes) && (def->mem.access != VIR_DOMAIN_MEMORY_ACCESS_SHARED)) {
> virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
> - _("virtiofs requires one or more NUMA nodes"));
> + _("virtiofs requires shared memory"));
> return -1;
> - }
> -
> - for (i = 0; i < numa_nodes; i++) {
> - virDomainMemoryAccess node_access =
> - virDomainNumaGetNodeMemoryAccessMode(def->numa, i);
> + } else {
> + for (i = 0; i < numa_nodes; i++) {
> + virDomainMemoryAccess node_access =
> + virDomainNumaGetNodeMemoryAccessMode(def->numa, i);
>
> - switch (node_access) {
> - case VIR_DOMAIN_MEMORY_ACCESS_DEFAULT:
> - if (def->mem.access != VIR_DOMAIN_MEMORY_ACCESS_SHARED) {
> + switch (node_access) {
> + case VIR_DOMAIN_MEMORY_ACCESS_DEFAULT:
> + if (def->mem.access != VIR_DOMAIN_MEMORY_ACCESS_SHARED) {
> + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
> + _("virtiofs requires shared memory"));
> + return -1;
> + }
> + break;
> + case VIR_DOMAIN_MEMORY_ACCESS_SHARED:
> + break;
> + case VIR_DOMAIN_MEMORY_ACCESS_PRIVATE:
> virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
> _("virtiofs requires shared memory"));
> return -1;
> - }
> - break;
> - case VIR_DOMAIN_MEMORY_ACCESS_SHARED:
> - break;
> - case VIR_DOMAIN_MEMORY_ACCESS_PRIVATE:
> - virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
> - _("virtiofs requires shared memory"));
> - return -1;
>
> - case VIR_DOMAIN_MEMORY_ACCESS_LAST:
> - default:
> - virReportEnumRangeError(virDomainMemoryAccess, node_access);
> - return -1;
> + case VIR_DOMAIN_MEMORY_ACCESS_LAST:
> + default:
> + virReportEnumRangeError(virDomainMemoryAccess, node_access);
> + return -1;
>
> + }
> }
> }
> return 0;
> --
> 2.27.0
>
> Thanks,
> Masa
>
