Re: [PATCH v3 2/2] ppc/spapr: Initialize max_cpus limit to SPAPR_IRQ_NR_IPIS.
On 23/11/23 14:21, Cédric Le Goater wrote: On 11/23/23 06:57, Harsh Prateek Bora wrote: Initialize the machine specific max_cpus limit as per the maximum range of CPU IPIs available. Keeping between 4096 to 8192 will throw IRQ not free error due to XIVE/XICS limitation and keeping beyond 8192 will hit assert in tcg_region_init or spapr_xive_claim_irq. Logs: Without patch fix: [root@host build]# qemu-system-ppc64 -accel tcg -smp 10,maxcpus=4097 qemu-system-ppc64: IRQ 4096 is not free [root@host build]# On LPAR: [root@host build]# qemu-system-ppc64 -accel tcg -smp 10,maxcpus=8193 ** ERROR:../tcg/region.c:774:tcg_region_init: assertion failed: (region_size >= 2 * page_size) Bail out! ERROR:../tcg/region.c:774:tcg_region_init: assertion failed: (region_size >= 2 * page_size) Aborted (core dumped) [root@host build]# On x86: [root@host build]# qemu-system-ppc64 -accel tcg -smp 10,maxcpus=8193 qemu-system-ppc64: ../hw/intc/spapr_xive.c:596: spapr_xive_claim_irq: Assertion `lisn < xive->nr_irqs' failed. Aborted (core dumped) [root@host build]# With patch fix: [root@host build]# qemu-system-ppc64 -accel tcg -smp 10,maxcpus=4097 qemu-system-ppc64: Invalid SMP CPUs 4097. The max CPUs supported by machine 'pseries-8.2' is 4096 [root@host build]# Signed-off-by: Harsh Prateek Bora Reviewed-by: Cédric Le Goater Thanks, C. --- hw/ppc/spapr.c | 9 +++-- 1 file changed, 3 insertions(+), 6 deletions(-) diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c index df09aa9d6a..222d926f46 100644 --- a/hw/ppc/spapr.c +++ b/hw/ppc/spapr.c @@ -4647,13 +4647,10 @@ static void spapr_machine_class_init(ObjectClass *oc, void *data) mc->block_default_type = IF_SCSI; /* - * Setting max_cpus to INT32_MAX. Both KVM and TCG max_cpus values - * should be limited by the host capability instead of hardcoded. - * max_cpus for KVM guests will be checked in kvm_init(), and TCG - * guests are welcome to have as many CPUs as the host are capable - * of emulate. + * While KVM determines max cpus in kvm_init() using kvm_max_vcpus(), + * In TCG the limit is restricted by the range of CPU IPIs available. */ - mc->max_cpus = INT32_MAX; + mc->max_cpus = SPAPR_IRQ_NR_IPIS; mc->no_parallel = 1; mc->default_boot_order = ""; I've applied these patches and verified on the latest upstream qemu. The code is working as expected. Tested-by: Kowshik Jois
Re: [PATCH v3 2/2] ppc/spapr: Initialize max_cpus limit to SPAPR_IRQ_NR_IPIS.
On 11/23/23 06:57, Harsh Prateek Bora wrote: Initialize the machine specific max_cpus limit as per the maximum range of CPU IPIs available. Keeping between 4096 to 8192 will throw IRQ not free error due to XIVE/XICS limitation and keeping beyond 8192 will hit assert in tcg_region_init or spapr_xive_claim_irq. Logs: Without patch fix: [root@host build]# qemu-system-ppc64 -accel tcg -smp 10,maxcpus=4097 qemu-system-ppc64: IRQ 4096 is not free [root@host build]# On LPAR: [root@host build]# qemu-system-ppc64 -accel tcg -smp 10,maxcpus=8193 ** ERROR:../tcg/region.c:774:tcg_region_init: assertion failed: (region_size >= 2 * page_size) Bail out! ERROR:../tcg/region.c:774:tcg_region_init: assertion failed: (region_size >= 2 * page_size) Aborted (core dumped) [root@host build]# On x86: [root@host build]# qemu-system-ppc64 -accel tcg -smp 10,maxcpus=8193 qemu-system-ppc64: ../hw/intc/spapr_xive.c:596: spapr_xive_claim_irq: Assertion `lisn < xive->nr_irqs' failed. Aborted (core dumped) [root@host build]# With patch fix: [root@host build]# qemu-system-ppc64 -accel tcg -smp 10,maxcpus=4097 qemu-system-ppc64: Invalid SMP CPUs 4097. The max CPUs supported by machine 'pseries-8.2' is 4096 [root@host build]# Signed-off-by: Harsh Prateek Bora Reviewed-by: Cédric Le Goater Thanks, C. --- hw/ppc/spapr.c | 9 +++-- 1 file changed, 3 insertions(+), 6 deletions(-) diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c index df09aa9d6a..222d926f46 100644 --- a/hw/ppc/spapr.c +++ b/hw/ppc/spapr.c @@ -4647,13 +4647,10 @@ static void spapr_machine_class_init(ObjectClass *oc, void *data) mc->block_default_type = IF_SCSI; /* - * Setting max_cpus to INT32_MAX. Both KVM and TCG max_cpus values - * should be limited by the host capability instead of hardcoded. - * max_cpus for KVM guests will be checked in kvm_init(), and TCG - * guests are welcome to have as many CPUs as the host are capable - * of emulate. + * While KVM determines max cpus in kvm_init() using kvm_max_vcpus(), + * In TCG the limit is restricted by the range of CPU IPIs available. */ -mc->max_cpus = INT32_MAX; +mc->max_cpus = SPAPR_IRQ_NR_IPIS; mc->no_parallel = 1; mc->default_boot_order = "";
[PATCH v3 2/2] ppc/spapr: Initialize max_cpus limit to SPAPR_IRQ_NR_IPIS.
Initialize the machine specific max_cpus limit as per the maximum range of CPU IPIs available. Keeping between 4096 to 8192 will throw IRQ not free error due to XIVE/XICS limitation and keeping beyond 8192 will hit assert in tcg_region_init or spapr_xive_claim_irq. Logs: Without patch fix: [root@host build]# qemu-system-ppc64 -accel tcg -smp 10,maxcpus=4097 qemu-system-ppc64: IRQ 4096 is not free [root@host build]# On LPAR: [root@host build]# qemu-system-ppc64 -accel tcg -smp 10,maxcpus=8193 ** ERROR:../tcg/region.c:774:tcg_region_init: assertion failed: (region_size >= 2 * page_size) Bail out! ERROR:../tcg/region.c:774:tcg_region_init: assertion failed: (region_size >= 2 * page_size) Aborted (core dumped) [root@host build]# On x86: [root@host build]# qemu-system-ppc64 -accel tcg -smp 10,maxcpus=8193 qemu-system-ppc64: ../hw/intc/spapr_xive.c:596: spapr_xive_claim_irq: Assertion `lisn < xive->nr_irqs' failed. Aborted (core dumped) [root@host build]# With patch fix: [root@host build]# qemu-system-ppc64 -accel tcg -smp 10,maxcpus=4097 qemu-system-ppc64: Invalid SMP CPUs 4097. The max CPUs supported by machine 'pseries-8.2' is 4096 [root@host build]# Signed-off-by: Harsh Prateek Bora --- hw/ppc/spapr.c | 9 +++-- 1 file changed, 3 insertions(+), 6 deletions(-) diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c index df09aa9d6a..222d926f46 100644 --- a/hw/ppc/spapr.c +++ b/hw/ppc/spapr.c @@ -4647,13 +4647,10 @@ static void spapr_machine_class_init(ObjectClass *oc, void *data) mc->block_default_type = IF_SCSI; /* - * Setting max_cpus to INT32_MAX. Both KVM and TCG max_cpus values - * should be limited by the host capability instead of hardcoded. - * max_cpus for KVM guests will be checked in kvm_init(), and TCG - * guests are welcome to have as many CPUs as the host are capable - * of emulate. + * While KVM determines max cpus in kvm_init() using kvm_max_vcpus(), + * In TCG the limit is restricted by the range of CPU IPIs available. */ -mc->max_cpus = INT32_MAX; +mc->max_cpus = SPAPR_IRQ_NR_IPIS; mc->no_parallel = 1; mc->default_boot_order = ""; -- 2.39.3
