On 04/05/2010 01:30 PM, Ky Srinivasan wrote:
+static cycle_t read_hv_clock(struct clocksource *arg)
+{
+ cycle_t current_tick;
+ /*
+ * Read the partition counter to get the current tick count. This count
+ * is set to 0 when the partition is created and is incremented in
+ * 100 nanosecond units.
+ */
+ rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
+ return current_tick;
+}
+
+static struct clocksource clocksource_hyperv = {
+ .name = "hyperv_clocksource",
Seems like a redundantly long name; any use of this string is going to
be in a context where it is obviously a clocksource. How about just
"hyperv"?
+ .rating = 400, /* use this when running on Hyperv*/
+ .read = read_hv_clock,
+ .mask = CLOCKSOURCE_MASK(64),
+ .shift = HV_CLOCK_SHIFT,
+};
+
+static struct dmi_system_id __initconst
+hv_timesource_dmi_table[] __maybe_unused = {
+ {
+ .ident = "Hyper-V",
+ .matches = {
+ DMI_MATCH(DMI_SYS_VENDOR, "Microsoft Corporation"),
+ DMI_MATCH(DMI_PRODUCT_NAME, "Virtual Machine"),
+ DMI_MATCH(DMI_BOARD_NAME, "Virtual Machine"),
+ },
+ },
+ { },
+};
+MODULE_DEVICE_TABLE(dmi, hv_timesource_dmi_table);
So you use the DMI signatures to determine whether the module is needed,
but cpuid to work out if the feature is present?
+
+static struct pci_device_id __initconst
+hv_timesource_pci_table[] __maybe_unused = {
+ { PCI_DEVICE(0x1414, 0x5353) }, /* VGA compatible controller */
+ { 0 }
+};
+MODULE_DEVICE_TABLE(pci, hv_timesource_pci_table);
And/or PCI?
Seems a bit... ad-hoc? Is this the official way to determine the
presence of Hyper-V?
+
+
+static int __init hv_detect_hyperv(void)
This looks generally useful. Should it be hidden away in the
clocksource driver, or in some common hyper-v code? Do other hyper-v
drivers have versions of this?
+{
+ u32 eax, ebx, ecx, edx;
+ static char hyp_signature[20];
20? static?
+
+ cpuid(1,&eax,&ebx,&ecx,&edx);
+ if (!(ecx& HV_HYPERVISOR_PRESENT_BIT)) {
+ printk(KERN_WARNING
+ "Not on a Hypervisor\n");
This just looks like noise, especially since it doesn't identify what is
generating the message. And if you compile this code in as =y
(non-modular) then it will complain every boot.
+ return 1;
+ }
+ cpuid(HV_CPUID_SIGNATURE,&eax,&ebx,&ecx,&edx);
+ *(u32 *)(hyp_signature + 0) = ebx;
+ *(u32 *)(hyp_signature + 4) = ecx;
+ *(u32 *)(hyp_signature + 8) = edx;
+ hyp_signature[12] = 0;
+
+ if ((eax< HV_CPUID_MIN) || (strcmp("Microsoft Hv", hyp_signature))) {
memcmp, surely?
+ printk(KERN_WARNING
+ "Not on HyperV; signature %s, eax %x\n",
+ hyp_signature, eax);
+ return 1;
+ }
+ /*
+ * Extract the features, recommendations etc.
+ */
+ cpuid(HV_CPUID_FEATURES,&eax,&ebx,&ecx,&edx);
+ if (!(eax& 0x10)) {
+ printk(KERN_WARNING "HyperV Time Ref Counter not available!\n");
+ return 1;
+ }
+
+ cpuid(HV_CPUID_RECOMMENDATIONS,&eax,&ebx,&ecx,&edx);
+ printk(KERN_INFO "HyperV recommendations: %x\n", eax);
+ printk(KERN_INFO "HyperV spin count: %x\n", ebx);
+ return 0;
+}
+
+
+static int __init init_hv_clocksource(void)
+{
+ if (hv_detect_hyperv())
+ return -ENODEV;
+ /*
+ * The time ref counter in HyperV is in 100ns units.
+ * The definition of mult is:
+ * mult/2^shift = ns/cyc = 100
+ * mult = (100<< shift)
+ */
+ clocksource_hyperv.mult = (100<< HV_CLOCK_SHIFT);
Why not initialize this in the structure? It's just 100<<22 isn't it?
+ printk(KERN_INFO "Registering HyperV clock source\n");
+ return clocksource_register(&clocksource_hyperv);
+}
+
+module_init(init_hv_clocksource);
+MODULE_DESCRIPTION("HyperV based clocksource");
+MODULE_AUTHOR("K. Y. Srinivasan<ksrinivasan@xxxxxxxxxx>");
+MODULE_LICENSE("GPL");
Index: linux/drivers/staging/hv/Makefile
===================================================================
--- linux.orig/drivers/staging/hv/Makefile 2010-04-05 13:02:06.000000000 -0600
+++ linux/drivers/staging/hv/Makefile 2010-04-05 13:02:13.000000000 -0600
@@ -1,4 +1,4 @@
-obj-$(CONFIG_HYPERV) += hv_vmbus.o
+obj-$(CONFIG_HYPERV) += hv_vmbus.o hv_timesource.o
obj-$(CONFIG_HYPERV_STORAGE) += hv_storvsc.o
obj-$(CONFIG_HYPERV_BLOCK) += hv_blkvsc.o
obj-$(CONFIG_HYPERV_NET) += hv_netvsc.o
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