linux-kernel - [PATCH v2 3/4] powerpc/kvm: Add vpa latency counters to kvm_vcpu

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Message-ID: <20241118114114.208964-3-kjain@linux.ibm.com>
Date: Mon, 18 Nov 2024 17:11:13 +0530
From: Kajol Jain <kjain@...ux.ibm.com>
To: mpe@...erman.id.au, maddy@...ux.ibm.com
Cc: atrajeev@...ux.vnet.ibm.com, kjain@...ux.ibm.com, disgoel@...ux.ibm.com,
        hbathini@...ux.ibm.com, adubey@...ux.ibm.com, gautam@...ux.ibm.com,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        Kajol Jain <kjain@...ux.ibm.com>
Subject: [PATCH v2 3/4] powerpc/kvm: Add vpa latency counters to kvm_vcpu_arch

Commit e1f288d2f9c69 ("KVM: PPC: Book3S HV nestedv2: Add support
for reading VPA counters for pseries guests") introduced support for new
Virtual Process Area(VPA) based software counters. These counters are
useful when observing context switch latency of L1 <-> L2. It also
added access to counters in lppaca, which is good enough to understand
latency details per-cpu level. But to extend and aggregate
per-process level(qemu) or per-pid/tid level(vcpu), these
counters also needs to be added as part of kvm_vcpu_arch struct.
Additional code added to update these new kvm_vcpu_arch variables
in do_trace_nested_cs_time function.

Signed-off-by: Kajol Jain <kjain@...ux.ibm.com>
Co-developed-by: Madhavan Srinivasan <maddy@...ux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@...ux.ibm.com>
---
 arch/powerpc/include/asm/kvm_host.h | 5 +++++
 arch/powerpc/kvm/book3s_hv.c        | 3 +++
 2 files changed, 8 insertions(+)

diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 37e581c5b201..6e1108f8fce6 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -871,6 +871,11 @@ struct kvm_vcpu_arch {
 	struct kvmhv_tb_accumulator cede_time;	/* time napping inside guest */
 #endif
 #endif /* CONFIG_KVM_BOOK3S_HV_EXIT_TIMING */
+#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
+	u64 l1_to_l2_cs;
+	u64 l2_to_l1_cs;
+	u64 l2_runtime_agg;
+#endif
 };
 
 #define VCPU_FPR(vcpu, i)	(vcpu)->arch.fp.fpr[i][TS_FPROFFSET]
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index e618533dfc4b..4284437fedeb 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -4191,6 +4191,9 @@ static void do_trace_nested_cs_time(struct kvm_vcpu *vcpu)
 	*l1_to_l2_cs_ptr = l1_to_l2_ns;
 	*l2_to_l1_cs_ptr = l2_to_l1_ns;
 	*l2_runtime_agg_ptr = l2_runtime_ns;
+	vcpu->arch.l1_to_l2_cs = l1_to_l2_ns;
+	vcpu->arch.l2_to_l1_cs = l2_to_l1_ns;
+	vcpu->arch.l2_runtime_agg = l2_runtime_ns;
 }
 
 u64 kvmhv_get_l1_to_l2_cs_time(void)
-- 
2.43.5