Re: [PATCH v2 4/4] xen/cppc: introduce cppc data upload sub-hypercall

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Adding Rafael and Len. and again keeping the full patch.

On 2024-12-05 00:42, Penny Zheng wrote:
As Xen is uncapable of parsing the ACPI dynamic table, this commit

s/uncapable/incapable/

introduces a new sub-hypercall XEN_PM_CPPC to deliver CPPC perf
caps data.

Signed-off-by: Penny Zheng <Penny.Zheng@xxxxxxx>
---
  drivers/acpi/cppc_acpi.c         |  1 +
  drivers/xen/xen-acpi-processor.c | 89 +++++++++++++++++++++++++++++++-
  include/acpi/processor.h         |  1 +
  include/xen/interface/platform.h | 11 ++++
  4 files changed, 101 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index 3a436591da07..3570a52a5dbd 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -860,6 +860,7 @@ static int acpi_cppc_processor_parse(struct acpi_processor *pr, struct cpc_desc
  		cpc_ptr->cpc_regs[i].cpc_entry.int_value = 0;
  	}
+ pr->flags.has_cpc = 1;
  	pr_debug("Parsed _CPC entry for CPU: %d\n", pr->acpi_id);
  	kfree(output.pointer);
  	return 0;
diff --git a/drivers/xen/xen-acpi-processor.c b/drivers/xen/xen-acpi-processor.c
index e9f38f171240..8a39e46c1ebc 100644
--- a/drivers/xen/xen-acpi-processor.c
+++ b/drivers/xen/xen-acpi-processor.c
@@ -25,6 +25,7 @@
  #include <xen/xen.h>
  #include <xen/interface/platform.h>
  #include <asm/xen/hypercall.h>
+#include <acpi/cppc_acpi.h>
static int no_hypercall;
  MODULE_PARM_DESC(off, "Inhibit the hypercall.");
@@ -45,8 +46,12 @@ static unsigned long *acpi_ids_done;
  static unsigned long *acpi_id_present;
  /* And if there is an _CST definition (or a PBLK) for the ACPI IDs */
  static unsigned long *acpi_id_cst_present;
+/* And if there is an _CPC entry for the ACPI IDs */
+static unsigned long *acpi_id_cpc_present;
  /* Which ACPI P-State dependencies for a enumerated processor */
  static struct acpi_psd_package *acpi_psd;
+/* ACPI CPPC structures for a enumerated processor */
+static struct cppc_perf_caps *acpi_cppc_data;
static bool pr_initialized; @@ -208,6 +213,44 @@ static int xen_copy_pct_data(struct acpi_pct_register *pct,
  	dst_pct->address = pct->address;
  	return 0;
  }
+static int push_cppc_to_hypervisor(struct acpi_processor *_pr)
+{
+	int ret = 0;
+	struct xen_platform_op op = {
+		.cmd            = XENPF_set_processor_pminfo,
+		.interface_version  = XENPF_INTERFACE_VERSION,
+		.u.set_pminfo.id    = _pr->acpi_id,
+		.u.set_pminfo.type  = XEN_PM_CPPC,
+	};
+	struct cppc_perf_caps *cppc_perf = acpi_cppc_data + _pr->acpi_id;
+
+	op.u.set_pminfo.cppc_data.highest_perf = cppc_perf->highest_perf;
+	op.u.set_pminfo.cppc_data.lowest_perf = cppc_perf->lowest_perf;
+	op.u.set_pminfo.cppc_data.nominal_perf = cppc_perf->nominal_perf;
+	op.u.set_pminfo.cppc_data.lowest_nonlinear_perf = cppc_perf->lowest_nonlinear_perf;
+	op.u.set_pminfo.cppc_data.lowest_freq = cppc_perf->lowest_freq;
+	op.u.set_pminfo.cppc_data.nominal_freq = cppc_perf->nominal_freq;
+
+	if (!no_hypercall)
+		ret = HYPERVISOR_platform_op(&op);
+
+	if (!ret) {
+		pr_debug("ACPI CPU%u - CPPC uploaded.\n", _pr->acpi_id);
+		pr_debug("     highest_perf: %d\n", cppc_perf->highest_perf);
+		pr_debug("     lowest_perf: %d\n", cppc_perf->lowest_perf);
+		pr_debug("     lowest_nonlinear_perf: %d\n", cppc_perf->lowest_nonlinear_perf);
+		pr_debug("     nominal_perf: %d\n", cppc_perf->nominal_perf);
+		pr_debug("     lowest_freq: %d Mhz\n", cppc_perf->lowest_freq);
+		pr_debug("     nominal_freq: %d Mhz\n", cppc_perf->nominal_freq);
+	} else if ((ret != -EINVAL) && (ret != -ENOSYS))
+		/* EINVAL means the ACPI ID is incorrect - meaning the ACPI
+		 * table is referencing a non-existing CPU - which can happen
+		 * with broken ACPI tables. */
+		pr_warn("(_CPC): Hypervisor error (%d) for ACPI CPU%u\n",
+			ret, _pr->acpi_id);
+
+		return ret;
+}
  static int push_pxx_to_hypervisor(struct acpi_processor *_pr)
  {
  	int ret = 0;
@@ -284,6 +327,9 @@ static int upload_pm_data(struct acpi_processor *_pr)
  	if (_pr->flags.power)
  		err = push_cxx_to_hypervisor(_pr);
+ if (_pr->flags.has_cpc)
+		err |= push_cppc_to_hypervisor(_pr);
+

Older hypervisors without the xen changes will return an error since they don't implement XEN_PM_CPPC. We might want to ignore the return when it's EINVAL, the default for the XEN_PM_* switch, but that may ignore more than intended.

The two calls to upload_pm_data() ignore the return value, so maybe it doesn't matter.

(This is the end of my comments.)

Thanks,
Jason

  	if (_pr->performance && _pr->performance->states)
  		err |= push_pxx_to_hypervisor(_pr);
@@ -488,6 +534,7 @@ read_acpi_id(acpi_handle handle, u32 lvl, void *context, void **rv)
  	union acpi_object object = { 0 };
  	struct acpi_buffer buffer = { sizeof(union acpi_object), &object };
  	struct acpi_buffer cst_buf = { ACPI_ALLOCATE_BUFFER, NULL };
+	struct acpi_buffer cpc_buf = { ACPI_ALLOCATE_BUFFER, NULL };
  	acpi_io_address pblk = 0;
status = acpi_get_type(handle, &acpi_type);
@@ -567,11 +614,20 @@ read_acpi_id(acpi_handle handle, u32 lvl, void *context, void **rv)
  	/* .. and it has a C-state */
  	__set_bit(acpi_id, acpi_id_cst_present);
+ status = acpi_evaluate_object(handle, "_CPC", NULL, &cpc_buf);
+	if (ACPI_FAILURE(status)) {
+		return AE_OK;
+	}
+	kfree(cpc_buf.pointer);
+
+	/* .. and it has a _CPC entry */
+	__set_bit(acpi_id, acpi_id_cpc_present);
+
  	return AE_OK;
  }
  static int check_acpi_ids(struct acpi_processor *pr_backup)
  {
-	if (acpi_id_present && acpi_id_cst_present)
+	if (acpi_id_present && acpi_id_cst_present && acpi_id_cpc_present)
  		/* OK, done this once .. skip to uploading */
  		goto upload;
@@ -588,11 +644,19 @@ static int check_acpi_ids(struct acpi_processor *pr_backup)
  		return -ENOMEM;
  	}
+ acpi_id_cpc_present = bitmap_zalloc(nr_acpi_bits, GFP_KERNEL);
+	if (!acpi_id_cpc_present) {
+		bitmap_free(acpi_id_present);
+		bitmap_free(acpi_id_cst_present);
+		return -ENOMEM;
+	}
+
  	acpi_psd = kcalloc(nr_acpi_bits, sizeof(struct acpi_psd_package),
  			   GFP_KERNEL);
  	if (!acpi_psd) {
  		bitmap_free(acpi_id_present);
  		bitmap_free(acpi_id_cst_present);
+		bitmap_free(acpi_id_cpc_present);
  		return -ENOMEM;
  	}
@@ -608,6 +672,12 @@ static int check_acpi_ids(struct acpi_processor *pr_backup)
  			pr_backup->acpi_id = i;
  			/* Mask out C-states if there are no _CST or PBLK */
  			pr_backup->flags.power = test_bit(i, acpi_id_cst_present);
+			/* Mask out relevant flag if there are no _CPC */
+			pr_backup->flags.has_cpc = test_bit(i, acpi_id_cpc_present);
+			if (pr_backup->flags.has_cpc) {
+				if (xen_processor_get_perf_caps(pr_backup, acpi_cppc_data + i))
+					return -EINVAL;
+			}
  			/* num_entries is non-zero if we evaluated _PSD */
  			if (acpi_psd[i].num_entries) {
  				memcpy(&pr_backup->performance->domain_info,
@@ -726,6 +796,15 @@ static int __init xen_acpi_processor_init(void)
  		bitmap_free(acpi_ids_done);
  		return -ENOMEM;
  	}
+
+	acpi_cppc_data = kcalloc(nr_acpi_bits, sizeof(struct cppc_perf_caps),
+				GFP_KERNEL);
+	if (!acpi_cppc_data) {
+		pr_debug("Memory allocation error for acpi_cppc_data\n");
+		rc = -ENOMEM;
+		goto err1_out;
+	}
+
  	for_each_possible_cpu(i) {
  		if (!zalloc_cpumask_var_node(
  			&per_cpu_ptr(acpi_perf_data, i)->shared_cpu_map,
@@ -751,6 +830,11 @@ static int __init xen_acpi_processor_init(void)
  		rc = acpi_processor_get_performance_info(pr);
  		if (rc)
  			goto err_out;
+
+		pr->flags.pcc_unsupported = true;
+		rc = xen_processor_get_perf_caps(pr, acpi_cppc_data + i);
+		if (rc)
+			goto err_out;
  	}
rc = xen_upload_processor_pm_data();
@@ -766,6 +850,8 @@ static int __init xen_acpi_processor_init(void)
err_out:
  	/* Freeing a NULL pointer is OK: alloc_percpu zeroes. */
+	kfree(acpi_cppc_data);
+err1_out:
  	free_acpi_perf_data();
  	bitmap_free(acpi_ids_done);
  	return rc;
@@ -779,6 +865,7 @@ static void __exit xen_acpi_processor_exit(void)
  	bitmap_free(acpi_id_present);
  	bitmap_free(acpi_id_cst_present);
  	kfree(acpi_psd);
+	kfree(acpi_cppc_data);
  	for_each_possible_cpu(i)
  		acpi_processor_unregister_performance(i);
diff --git a/include/acpi/processor.h b/include/acpi/processor.h
index 18499cc11366..66492f5d68a8 100644
--- a/include/acpi/processor.h
+++ b/include/acpi/processor.h
@@ -214,6 +214,7 @@ struct acpi_processor_flags {
  	u8 bm_control:1;
  	u8 bm_check:1;
  	u8 has_cst:1;
+	u8 has_cpc:1;
  	u8 pcc_unsupported:1;
  	u8 has_lpi:1;
  	u8 power_setup_done:1;
diff --git a/include/xen/interface/platform.h b/include/xen/interface/platform.h
index 79a443c65ea9..e11bb9443dc0 100644
--- a/include/xen/interface/platform.h
+++ b/include/xen/interface/platform.h
@@ -319,6 +319,7 @@ DEFINE_GUEST_HANDLE_STRUCT(xenpf_getidletime_t);
  #define XEN_PM_PX   1
  #define XEN_PM_TX   2
  #define XEN_PM_PDC  3
+#define XEN_PM_CPPC 4
  /* Px sub info type */
  #define XEN_PX_PCT   1
  #define XEN_PX_PSS   2
@@ -384,6 +385,15 @@ struct xen_processor_px {
  };
  DEFINE_GUEST_HANDLE_STRUCT(xen_processor_px);
+struct xen_processor_cppc {
+    uint32_t highest_perf;
+    uint32_t nominal_perf;
+    uint32_t lowest_perf;
+    uint32_t lowest_nonlinear_perf;
+    uint32_t lowest_freq;
+    uint32_t nominal_freq;
+};
+
  struct xen_psd_package {
  	uint64_t num_entries;
  	uint64_t revision;
@@ -412,6 +422,7 @@ struct xenpf_set_processor_pminfo {
  		struct xen_processor_power          power;/* Cx: _CST/_CSD */
  		struct xen_processor_performance    perf; /* Px: _PPC/_PCT/_PSS/_PSD */
  		GUEST_HANDLE(uint32_t)              pdc;
+		struct xen_processor_cppc           cppc_data; /* _CPC */
  	};
  };
  DEFINE_GUEST_HANDLE_STRUCT(xenpf_set_processor_pminfo);





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