KVM: PPC: Book3S HV: Decouple the debug timing from the P8 entry path

We are currently doing the timing for debug purposes of the P9 entry
path using the accumulators and terminology defined by the old entry
path for P8 machines.

Not only the "real-mode" and "napping" mentions are out of place for
the P9 Radix entry path but also we cannot change them because the
timing code is coupled to the structures defined in struct
kvm_vcpu_arch.

Add a new CONFIG_KVM_BOOK3S_HV_P9_TIMING to enable the timing code for
the P9 entry path. For now, just add the new CONFIG and duplicate the
structures. A subsequent patch will add the P9 changes.
Signed-off-by: Fabiano Rosas <farosas@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220525130554.2614394-4-farosas@linux.ibm.com

arch/powerpc/include/asm/kvm_host.h

@@ -830,11 +830,19 @@ struct kvm_vcpu_arch {
 #ifdef CONFIG_KVM_BOOK3S_HV_EXIT_TIMING
 	struct kvmhv_tb_accumulator *cur_activity;	/* What we're timing */
 	u64	cur_tb_start;			/* when it started */
+#ifdef CONFIG_KVM_BOOK3S_HV_P9_TIMING
 	struct kvmhv_tb_accumulator rm_entry;	/* real-mode entry code */
 	struct kvmhv_tb_accumulator rm_intr;	/* real-mode intr handling */
 	struct kvmhv_tb_accumulator rm_exit;	/* real-mode exit code */
 	struct kvmhv_tb_accumulator guest_time;	/* guest execution */
 	struct kvmhv_tb_accumulator cede_time;	/* time napping inside guest */
+#else
+	struct kvmhv_tb_accumulator rm_entry;	/* real-mode entry code */
+	struct kvmhv_tb_accumulator rm_intr;	/* real-mode intr handling */
+	struct kvmhv_tb_accumulator rm_exit;	/* real-mode exit code */
+	struct kvmhv_tb_accumulator guest_time;	/* guest execution */
+	struct kvmhv_tb_accumulator cede_time;	/* time napping inside guest */
+#endif
 #endif /* CONFIG_KVM_BOOK3S_HV_EXIT_TIMING */
 };
 

arch/powerpc/kvm/Kconfig

@@ -130,10 +130,22 @@ config KVM_BOOK3S_64_PR
 config KVM_BOOK3S_HV_EXIT_TIMING
 	bool
 
+config KVM_BOOK3S_HV_P9_TIMING
+	bool "Detailed timing for the P9 entry point"
+	select KVM_BOOK3S_HV_EXIT_TIMING
+	depends on KVM_BOOK3S_HV_POSSIBLE && DEBUG_FS
+	help
+	  Calculate time taken for each vcpu in various parts of the
+	  code. The total, minimum and maximum times in nanoseconds
+	  together with the number of executions are reported in debugfs in
+	  kvm/vm#/vcpu#/timings.
+
+	  If unsure, say N.
+
 config KVM_BOOK3S_HV_P8_TIMING
 	bool "Detailed timing for hypervisor real-mode code (for POWER8)"
 	select KVM_BOOK3S_HV_EXIT_TIMING
-	depends on KVM_BOOK3S_HV_POSSIBLE && DEBUG_FS
+	depends on KVM_BOOK3S_HV_POSSIBLE && DEBUG_FS && !KVM_BOOK3S_HV_P9_TIMING
 	help
 	  Calculate time taken for each vcpu in the real-mode guest entry,
 	  exit, and interrupt handling code, plus time spent in the guest

arch/powerpc/kvm/book3s_hv.c

@@ -2660,11 +2660,19 @@ static struct debugfs_timings_element {
 	const char *name;
 	size_t offset;
 } timings[] = {
+#ifdef CONFIG_KVM_BOOK3S_HV_P9_TIMING
 	{"rm_entry",	offsetof(struct kvm_vcpu, arch.rm_entry)},
 	{"rm_intr",	offsetof(struct kvm_vcpu, arch.rm_intr)},
 	{"rm_exit",	offsetof(struct kvm_vcpu, arch.rm_exit)},
 	{"guest",	offsetof(struct kvm_vcpu, arch.guest_time)},
 	{"cede",	offsetof(struct kvm_vcpu, arch.cede_time)},
+#else
+	{"rm_entry",	offsetof(struct kvm_vcpu, arch.rm_entry)},
+	{"rm_intr",	offsetof(struct kvm_vcpu, arch.rm_intr)},
+	{"rm_exit",	offsetof(struct kvm_vcpu, arch.rm_exit)},
+	{"guest",	offsetof(struct kvm_vcpu, arch.guest_time)},
+	{"cede",	offsetof(struct kvm_vcpu, arch.cede_time)},
+#endif
 };
 
 #define N_TIMINGS	(ARRAY_SIZE(timings))
@@ -2783,8 +2791,9 @@ static const struct file_operations debugfs_timings_ops = {
 /* Create a debugfs directory for the vcpu */
 static int kvmppc_arch_create_vcpu_debugfs_hv(struct kvm_vcpu *vcpu, struct dentry *debugfs_dentry)
 {
-	debugfs_create_file("timings", 0444, debugfs_dentry, vcpu,
-			    &debugfs_timings_ops);
+	if (cpu_has_feature(CPU_FTR_ARCH_300) == IS_ENABLED(CONFIG_KVM_BOOK3S_HV_P9_TIMING))
+		debugfs_create_file("timings", 0444, debugfs_dentry, vcpu,
+				    &debugfs_timings_ops);
 	return 0;
 }
 

arch/powerpc/kvm/book3s_hv_p9_entry.c

@@ -437,7 +437,7 @@ void restore_p9_host_os_sprs(struct kvm_vcpu *vcpu,
 }
 EXPORT_SYMBOL_GPL(restore_p9_host_os_sprs);
 
-#ifdef CONFIG_KVM_BOOK3S_HV_EXIT_TIMING
+#ifdef CONFIG_KVM_BOOK3S_HV_P9_TIMING
 static void __accumulate_time(struct kvm_vcpu *vcpu, struct kvmhv_tb_accumulator *next)
 {
 	struct kvmppc_vcore *vc = vcpu->arch.vcore;