[PATCH v8] arch/powerpc/kvm: Add support for reading VPA counters for pseries guests
PAPR hypervisor has introduced three new counters in the VPA area of
LPAR CPUs for KVM L2 guest (see [1] for terminology) observability - 2
for context switches from host to guest and vice versa, and 1 counter
for getting the total time spent inside the KVM guest. Add a tracepoint
that enables reading the counters for use by ftrace/perf. Note that this
tracepoint is only available for nestedv2 API (i.e, KVM on PowerVM).
[1] Terminology:
a. L1 refers to the VM (LPAR) booted on top of PAPR hypervisor
b. L2 refers to the KVM guest booted on top of L1.
Reviewed-by: Nicholas Piggin
Acked-by: Naveen N Rao
Signed-off-by: Vaibhav Jain
Signed-off-by: Gautam Menghani
---
v7 -> v8:
1. Use per_cpu vars instead of paca members.
2. Fix build error for powernv config.
v6 -> v7:
1. Use TRACE_EVENT_FN_COND to handle zero counters case.
2. Use for_each_present_cpu() to handle hotplugs.
v5 -> v6:
1. Use TRACE_EVENT_FN to enable/disable counters only once.
2. Remove the agg. counters from vcpu->arch.
3. Use PACA to maintain old counter values instead of zeroing on every
entry.
4. Simplify variable names
v4 -> v5:
1. Define helper functions for getting/setting the accumulation counter
in L2's VPA
v3 -> v4:
1. After vcpu_run, check the VPA flag instead of checking for tracepoint
being enabled for disabling the cs time accumulation.
v2 -> v3:
1. Move the counter disabling and zeroing code to a different function.
2. Move the get_lppaca() inside the tracepoint_enabled() branch.
3. Add the aggregation logic to maintain total context switch time.
v1 -> v2:
1. Fix the build error due to invalid struct member reference.
arch/powerpc/include/asm/kvm_book3s_64.h | 6 ++
arch/powerpc/include/asm/lppaca.h| 11 +++-
arch/powerpc/kvm/book3s_hv.c | 4 ++
arch/powerpc/kvm/book3s_hv_nestedv2.c| 80
arch/powerpc/kvm/trace_hv.h | 31 +
5 files changed, 129 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/include/asm/kvm_book3s_64.h
b/arch/powerpc/include/asm/kvm_book3s_64.h
index d8729ec81ca0..083f93881cbb 100644
--- a/arch/powerpc/include/asm/kvm_book3s_64.h
+++ b/arch/powerpc/include/asm/kvm_book3s_64.h
@@ -684,6 +684,12 @@ int kvmhv_nestedv2_set_ptbl_entry(unsigned long lpid, u64
dw0, u64 dw1);
int kvmhv_nestedv2_parse_output(struct kvm_vcpu *vcpu);
int kvmhv_nestedv2_set_vpa(struct kvm_vcpu *vcpu, unsigned long vpa);
+int kvmhv_get_l2_counters_status(void);
+void kvmhv_set_l2_counters_status(int cpu, bool status);
+int kmvhv_counters_tracepoint_regfunc(void);
+void kmvhv_counters_tracepoint_unregfunc(void);
+void do_trace_nested_cs_time(struct kvm_vcpu *vcpu);
+
#endif /* CONFIG_KVM_BOOK3S_HV_POSSIBLE */
#endif /* __ASM_KVM_BOOK3S_64_H__ */
diff --git a/arch/powerpc/include/asm/lppaca.h
b/arch/powerpc/include/asm/lppaca.h
index 61ec2447dabf..f40a646bee3c 100644
--- a/arch/powerpc/include/asm/lppaca.h
+++ b/arch/powerpc/include/asm/lppaca.h
@@ -62,7 +62,8 @@ struct lppaca {
u8 donate_dedicated_cpu; /* Donate dedicated CPU cycles */
u8 fpregs_in_use;
u8 pmcregs_in_use;
- u8 reserved8[28];
+ u8 l2_counters_enable; /* Enable usage of counters for KVM guest
*/
+ u8 reserved8[27];
__be64 wait_state_cycles; /* Wait cycles for this proc */
u8 reserved9[28];
__be16 slb_count; /* # of SLBs to maintain */
@@ -92,9 +93,13 @@ struct lppaca {
/* cacheline 4-5 */
__be32 page_ins; /* CMO Hint - # page ins by OS */
- u8 reserved12[148];
+ u8 reserved12[28];
+ volatile __be64 l1_to_l2_cs_tb;
+ volatile __be64 l2_to_l1_cs_tb;
+ volatile __be64 l2_runtime_tb;
+ u8 reserved13[96];
volatile __be64 dtl_idx;/* Dispatch Trace Log head index */
- u8 reserved13[96];
+ u8 reserved14[96];
} cacheline_aligned;
#define lppaca_of(cpu) (*paca_ptrs[cpu]->lppaca_ptr)
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 8e86eb577eb8..2f49b3a5a4c0 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -4156,6 +4156,10 @@ static int kvmhv_vcpu_entry_nestedv2(struct kvm_vcpu
*vcpu, u64 time_limit,
timer_rearm_host_dec(*tb);
+ /* Record context switch and guest_run_time data */
+ if (kvmhv_get_l2_counters_status())
+ do_trace_nested_cs_time(vcpu);
+
return trap;
}
diff --git a/arch/powerpc/kvm/book3s_hv_nestedv2.c
b/arch/powerpc/kvm/book3s_hv_nestedv2.c
index 8e6f5355f08b..0a99ca137f7a 100644
--- a/arch/powerpc/kvm/book3s_hv_nestedv2.c
+++ b/arch/powerpc/kvm/book3s_hv_nestedv2.c
@@ -1037,3 +1037,83 @@ void kvmhv_nestedv2_vcpu_free(struct kvm_vcpu *vcpu,
kvmhv_nestedv2_host_free(vcpu, io);
}
EXPORT_SYMBOL_GPL(kvmhv_nestedv2_vcpu_free);
+
+/* Helper functions for reading L2's stats from L1's VPA */
+
+#ifdef CONFIG_PPC_PSER
Re: [PATCH v8] arch/powerpc/kvm: Add support for reading VPA counters for pseries guests
Hi Gautam, kernel test robot noticed the following build errors: [auto build test ERROR on powerpc/topic/ppc-kvm] [also build test ERROR on powerpc/next powerpc/fixes kvm/queue mst-vhost/linux-next linus/master v6.9 next-20240516] [cannot apply to kvm/linux-next] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch#_base_tree_information] url: https://github.com/intel-lab-lkp/linux/commits/Gautam-Menghani/arch-powerpc-kvm-Add-support-for-reading-VPA-counters-for-pseries-guests/20240510-185213 base: https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git topic/ppc-kvm patch link: https://lore.kernel.org/r/20240510104941.78410-1-gautam%40linux.ibm.com patch subject: [PATCH v8] arch/powerpc/kvm: Add support for reading VPA counters for pseries guests config: powerpc-allmodconfig (https://download.01.org/0day-ci/archive/20240517/202405170932.tl7g99ij-...@intel.com/config) compiler: powerpc64-linux-gcc (GCC) 13.2.0 reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240517/202405170932.tl7g99ij-...@intel.com/reproduce) If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags | Reported-by: kernel test robot | Closes: https://lore.kernel.org/oe-kbuild-all/202405170932.tl7g99ij-...@intel.com/ All errors (new ones prefixed by >>): powerpc64-linux-ld: warning: discarding dynamic section .glink powerpc64-linux-ld: warning: discarding dynamic section .plt powerpc64-linux-ld: linkage table error against `__traceiter_kvmppc_vcpu_stats' powerpc64-linux-ld: stubs don't match calculated size powerpc64-linux-ld: can not build stubs: bad value powerpc64-linux-ld: arch/powerpc/kvm/book3s_hv_nestedv2.o: in function `do_trace_nested_cs_time': >> book3s_hv_nestedv2.c:(.text.do_trace_nested_cs_time+0x264): undefined >> reference to `__traceiter_kvmppc_vcpu_stats' >> powerpc64-linux-ld: >> arch/powerpc/kvm/book3s_hv_nestedv2.o:(__jump_table+0x8): undefined >> reference to `__tracepoint_kvmppc_vcpu_stats' -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests/wiki
Re: [PATCH v8] arch/powerpc/kvm: Add support for reading VPA counters for pseries guests
Hi Gautam, kernel test robot noticed the following build errors: [auto build test ERROR on powerpc/topic/ppc-kvm] [also build test ERROR on powerpc/next powerpc/fixes kvm/queue mst-vhost/linux-next linus/master v6.9 next-20240517] [cannot apply to kvm/linux-next] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch#_base_tree_information] url: https://github.com/intel-lab-lkp/linux/commits/Gautam-Menghani/arch-powerpc-kvm-Add-support-for-reading-VPA-counters-for-pseries-guests/20240510-185213 base: https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git topic/ppc-kvm patch link: https://lore.kernel.org/r/20240510104941.78410-1-gautam%40linux.ibm.com patch subject: [PATCH v8] arch/powerpc/kvm: Add support for reading VPA counters for pseries guests config: powerpc-ppc64_defconfig (https://download.01.org/0day-ci/archive/20240518/202405180535.yomk4bga-...@intel.com/config) compiler: powerpc64-linux-gcc (GCC) 13.2.0 reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240518/202405180535.yomk4bga-...@intel.com/reproduce) If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags | Reported-by: kernel test robot | Closes: https://lore.kernel.org/oe-kbuild-all/202405180535.yomk4bga-...@intel.com/ All errors (new ones prefixed by >>): powerpc64-linux-ld: warning: discarding dynamic section .glink powerpc64-linux-ld: warning: discarding dynamic section .plt powerpc64-linux-ld: linkage table error against `__traceiter_kvmppc_vcpu_stats' powerpc64-linux-ld: stubs don't match calculated size powerpc64-linux-ld: can not build stubs: bad value powerpc64-linux-ld: arch/powerpc/kvm/book3s_hv_nestedv2.o: in function `do_trace_nested_cs_time': >> book3s_hv_nestedv2.c:(.text+0x4b4): undefined reference to >> `__traceiter_kvmppc_vcpu_stats' powerpc64-linux-ld: arch/powerpc/kvm/book3s_hv_nestedv2.o:(__jump_table+0x8): undefined reference to `__tracepoint_kvmppc_vcpu_stats' -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests/wiki
