Re: [PATCH 1/2] KVM: PPC: Book3S HV: Allow creating max number of VCPUs on POWER9
From: Sam Bobroff <hidden>
Date: 2018-07-30 03:37:39
Also in:
kvm
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 <redacted>
---
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 <redacted>
quoted hunk ↗ jump to hunk
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=
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