| Message ID | 20180726054353.GB1672@fergus (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/2] KVM: PPC: Book3S HV: Allow creating max number of VCPUs on POWER9 | expand |
On Thu, Jul 26, 2018 at 03:43:54PM +1000, Paul Mackerras wrote: > Commit 1e175d2 ("KVM: PPC: Book3S HV: Pack VCORE IDs to access full > VCPU ID space", 2018-07-25) allowed use of VCPU IDs up to > KVM_MAX_VCPU_ID on POWER9 in all guest SMT modes and guest emulated > hardware SMT modes. However, with the current definition of > KVM_MAX_VCPU_ID, a guest SMT mode of 1 and an emulated SMT mode of 8, > it is only possible to create KVM_MAX_VCPUS / 2 VCPUS, because > threads_per_subcore is 4 on POWER9 CPUs. (Using an emulated SMT mode > of 8 is useful when migrating VMs to or from POWER8 hosts.) > > This increases KVM_MAX_VCPU_ID to 8 * KVM_MAX_VCPUS when HV KVM is > configured in, so that a full complement of KVM_MAX_VCPUS VCPUs can > be created on POWER9 in all guest SMT modes and emulated hardware > SMT modes. > > Signed-off-by: Paul Mackerras <paulus@ozlabs.org> > --- > This and the next patch apply on my kvm-ppc-next branch, which > includes Sam Bobroff's patch "KVM: PPC: Book3S HV: Pack VCORE IDs to > access full VCPU ID space". Thanks! I've tested kvm-ppc-next with all three above patches, and I'm able to access the entire VCPU ID space (tested using CONFIG_NR_CPUS 1024 in the host, rather than the default 2048, as that's the limit imposed by QEMU). So: Tested-by: Sam Bobroff <sbobroff@linux.ibm.com> > > arch/powerpc/include/asm/kvm_host.h | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h > index 5b9e660..906bcbdf 100644 > --- a/arch/powerpc/include/asm/kvm_host.h > +++ b/arch/powerpc/include/asm/kvm_host.h > @@ -42,7 +42,14 @@ > #define KVM_USER_MEM_SLOTS 512 > > #include <asm/cputhreads.h> > -#define KVM_MAX_VCPU_ID (threads_per_subcore * KVM_MAX_VCORES) > + > +#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE > +#include <asm/kvm_book3s_asm.h> /* for MAX_SMT_THREADS */ > +#define KVM_MAX_VCPU_ID (MAX_SMT_THREADS * KVM_MAX_VCORES) > + > +#else > +#define KVM_MAX_VCPU_ID KVM_MAX_VCPUS > +#endif /* CONFIG_KVM_BOOK3S_HV_POSSIBLE */ > > #define __KVM_HAVE_ARCH_INTC_INITIALIZED > > -- > 2.7.4 > > -- > To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at https://urldefense.proofpoint.com/v2/url?u=http-3A__vger.kernel.org_majordomo-2Dinfo.html&d=DwIBAg&c=jf_iaSHvJObTbx-siA1ZOg&r=FFlZoKpUuHop_w02rKHYxbjM9foF4tIm4FyKg8muba0&m=XJuK_j7qbnfsRxN3uHJ65CPxG7brNIut6LNuFyQYF8k&s=2zUtzqXA51owzthAuMl8kD0fWpLcjXBZswb_t6SYFSI&e= >
diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h index 5b9e660..906bcbdf 100644 --- a/arch/powerpc/include/asm/kvm_host.h +++ b/arch/powerpc/include/asm/kvm_host.h @@ -42,7 +42,14 @@ #define KVM_USER_MEM_SLOTS 512 #include <asm/cputhreads.h> -#define KVM_MAX_VCPU_ID (threads_per_subcore * KVM_MAX_VCORES) + +#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE +#include <asm/kvm_book3s_asm.h> /* for MAX_SMT_THREADS */ +#define KVM_MAX_VCPU_ID (MAX_SMT_THREADS * KVM_MAX_VCORES) + +#else +#define KVM_MAX_VCPU_ID KVM_MAX_VCPUS +#endif /* CONFIG_KVM_BOOK3S_HV_POSSIBLE */ #define __KVM_HAVE_ARCH_INTC_INITIALIZED
Commit 1e175d2 ("KVM: PPC: Book3S HV: Pack VCORE IDs to access full VCPU ID space", 2018-07-25) allowed use of VCPU IDs up to KVM_MAX_VCPU_ID on POWER9 in all guest SMT modes and guest emulated hardware SMT modes. However, with the current definition of KVM_MAX_VCPU_ID, a guest SMT mode of 1 and an emulated SMT mode of 8, it is only possible to create KVM_MAX_VCPUS / 2 VCPUS, because threads_per_subcore is 4 on POWER9 CPUs. (Using an emulated SMT mode of 8 is useful when migrating VMs to or from POWER8 hosts.) This increases KVM_MAX_VCPU_ID to 8 * KVM_MAX_VCPUS when HV KVM is configured in, so that a full complement of KVM_MAX_VCPUS VCPUs can be created on POWER9 in all guest SMT modes and emulated hardware SMT modes. Signed-off-by: Paul Mackerras <paulus@ozlabs.org> --- This and the next patch apply on my kvm-ppc-next branch, which includes Sam Bobroff's patch "KVM: PPC: Book3S HV: Pack VCORE IDs to access full VCPU ID space". arch/powerpc/include/asm/kvm_host.h | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)