Re: [PATCH] KVM: PPC: Book3S HV: increase KVMPPC_NR_LPIDS on POWER8 and POWER9
From: Cédric Le Goater <clg@kaod.org>
Date: 2020-06-23 15:31:52
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kvm
On 6/8/20 1:57 PM, Cédric Le Goater wrote:
POWER8 and POWER9 have 12-bit LPIDs. Change LPID_RSVD to support up to (4096 - 2) guests on these processors. POWER7 is kept the same with a limitation of (1024 - 2), but it might be time to drop KVM support for POWER7. Tested with 2048 guests * 4 vCPUs on a witherspoon system with 512G RAM and a bit of swap.
For the record, it is possible to run 4094 guests * 4 vCPUs on a POWER9 system with 1TB. It takes ~5m to boot them all. CONFIG_NR_IRQS needs to be increased to support 4094 * 4 escalation interrupts. Cheers, C.
quoted hunk ↗ jump to hunk
Signed-off-by: Cédric Le Goater <clg@kaod.org> --- arch/powerpc/include/asm/reg.h | 3 ++- arch/powerpc/kvm/book3s_64_mmu_hv.c | 8 ++++++-- 2 files changed, 8 insertions(+), 3 deletions(-)diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h index 88e6c78100d9..b70bbfb0ea3c 100644 --- a/arch/powerpc/include/asm/reg.h +++ b/arch/powerpc/include/asm/reg.h@@ -473,7 +473,8 @@ #ifndef SPRN_LPID #define SPRN_LPID 0x13F /* Logical Partition Identifier */ #endif -#define LPID_RSVD 0x3ff /* Reserved LPID for partn switching */ +#define LPID_RSVD_POWER7 0x3ff /* Reserved LPID for partn switching */ +#define LPID_RSVD 0xfff /* Reserved LPID for partn switching */ #define SPRN_HMER 0x150 /* Hypervisor maintenance exception reg */ #define HMER_DEBUG_TRIG (1ul << (63 - 17)) /* Debug trigger */ #define SPRN_HMEER 0x151 /* Hyp maintenance exception enable reg */diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c index 18aed9775a3c..23035ab2ec50 100644 --- a/arch/powerpc/kvm/book3s_64_mmu_hv.c +++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c@@ -260,11 +260,15 @@ int kvmppc_mmu_hv_init(void) if (!mmu_has_feature(MMU_FTR_LOCKLESS_TLBIE)) return -EINVAL; - /* POWER7 has 10-bit LPIDs (12-bit in POWER8) */ host_lpid = 0; if (cpu_has_feature(CPU_FTR_HVMODE)) host_lpid = mfspr(SPRN_LPID); - rsvd_lpid = LPID_RSVD; + + /* POWER8 and above have 12-bit LPIDs (10-bit in POWER7) */ + if (cpu_has_feature(CPU_FTR_ARCH_207S)) + rsvd_lpid = LPID_RSVD; + else + rsvd_lpid = LPID_RSVD_POWER7; kvmppc_init_lpid(rsvd_lpid + 1);