On Wed, Feb 28, 2024 at 08:03:51PM +0530, Ani Sinha wrote: > Date: Wed, 28 Feb 2024 20:03:51 +0530 > From: Ani Sinha <anisi...@redhat.com> > Subject: [PATCH v5] pc: q35: Bump max_cpus to 4096 vcpus > X-Mailer: git-send-email 2.42.0 > > Since commit f10a570b093e6 ("KVM: x86: Add CONFIG_KVM_MAX_NR_VCPUS to allow > up to 4096 vCPUs") > Linux kernel can support upto a maximum number of 4096 vcpus when MAXSMP is > enabled in the kernel. At present, QEMU has been tested to correctly boot a > linux guest with 4096 vcpus using the current edk2 upstream master branch that > has the fixes corresponding to the following two PRs: > > https://github.com/tianocore/edk2/pull/5410 > https://github.com/tianocore/edk2/pull/5418 > > The changes merged into edk2 with the above PRs will be in the upcoming > 2024-05 > release. With current seabios firmware, it boots fine with 4096 vcpus already. > So bump up the value max_cpus to 4096 for q35 machines versions 9 and newer. > Q35 machines versions 8.2 and older continue to support 1024 maximum vcpus > as before for compatibility reasons. > > If KVM is not able to support the specified number of vcpus, QEMU would > return the following error messages: > > $ ./qemu-system-x86_64 -cpu host -accel kvm -machine q35 -smp 1728 > qemu-system-x86_64: -accel kvm: warning: Number of SMP cpus requested (1728) > exceeds the recommended cpus supported by KVM (12) > qemu-system-x86_64: -accel kvm: warning: Number of hotpluggable cpus > requested (1728) exceeds the recommended cpus supported by KVM (12) > Number of SMP cpus requested (1728) exceeds the maximum cpus supported by KVM > (1024) > > Cc: Daniel P. Berrangé <berra...@redhat.com> > Cc: Igor Mammedov <imamm...@redhat.com> > Cc: Michael S. Tsirkin <m...@redhat.com> > Cc: Julia Suvorova <jus...@redhat.com> > Cc: kra...@redhat.com > Reviewed-by: Daniel P. Berrangé <berra...@redhat.com> > Reviewed-by: Igor Mammedov <imamm...@redhat.com> > Reviewed-by: Gerd Hoffmann <kra...@redhat.com> > Signed-off-by: Ani Sinha <anisi...@redhat.com> > --- > hw/i386/pc_q35.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) >
Reviewed-by: Zhao Liu <zhao1....@intel.com>