#include <linux/bitops.h>
#include <linux/cpufeature.h>
#include <linux/cpumask.h>
+#include <linux/delay.h>
#include <linux/gfp.h>
#include <linux/io.h>
#include <linux/kernel.h>
wrmsrl(MSR_IA32_HW_FEEDBACK_PTR, msr_val);
}
+/* Caller must hold hfi_instance_lock. */
+static void hfi_disable(void)
+{
+ u64 msr_val;
+ int i;
+
+ rdmsrl(MSR_IA32_HW_FEEDBACK_CONFIG, msr_val);
+ msr_val &= ~HW_FEEDBACK_CONFIG_HFI_ENABLE_BIT;
+ wrmsrl(MSR_IA32_HW_FEEDBACK_CONFIG, msr_val);
+
+ /*
+ * Wait for hardware to acknowledge the disabling of HFI. Some
+ * processors may not do it. Wait for ~2ms. This is a reasonable
+ * time for hardware to complete any pending actions on the HFI
+ * memory.
+ */
+ for (i = 0; i < 2000; i++) {
+ rdmsrl(MSR_IA32_PACKAGE_THERM_STATUS, msr_val);
+ if (msr_val & PACKAGE_THERM_STATUS_HFI_UPDATED)
+ break;
+
+ udelay(1);
+ cpu_relax();
+ }
+}
+
/**
* intel_hfi_online() - Enable HFI on @cpu
* @cpu: CPU in which the HFI will be enabled
/*
* Hardware is programmed with the physical address of the first page
* frame of the table. Hence, the allocated memory must be page-aligned.
+ *
+ * Some processors do not forget the initial address of the HFI table
+ * even after having been reprogrammed. Keep using the same pages. Do
+ * not free them.
*/
hfi_instance->hw_table = alloc_pages_exact(hfi_features.nr_table_pages,
GFP_KERNEL | __GFP_ZERO);
mutex_lock(&hfi_instance_lock);
cpumask_clear_cpu(cpu, hfi_instance->cpus);
+
+ if (!cpumask_weight(hfi_instance->cpus))
+ hfi_disable();
+
mutex_unlock(&hfi_instance_lock);
}