Commit 558daa28 authored May 02, 2012 by Konrad Rzeszutek Wilk

xen/apic: Return the APIC ID (and version) for CPU 0.



On x86_64 on AMD machines where the first APIC_ID is not zero, we get:

ACPI: LAPIC (acpi_id[0x01] lapic_id[0x10] enabled)
BIOS bug: APIC version is 0 for CPU 1/0x10, fixing up to 0x10
BIOS bug: APIC version mismatch, boot CPU: 0, CPU 1: version 10

which means that when the ACPI processor driver loads and
tries to parse the _Pxx states it fails to do as, as it
ends up calling acpi_get_cpuid which does this:

for_each_possible_cpu(i) {
        if (cpu_physical_id(i) == apic_id)
                return i;
}

And the bootup CPU, has not been found so it fails and returns -1
for the first CPU - which then subsequently in the loop that
"acpi_processor_get_info" does results in returning an error, which
means that "acpi_processor_add" failing and per_cpu(processor)
is never set (and is NULL).

That means that when xen-acpi-processor tries to load (much much
later on) and parse the P-states it gets -ENODEV from
acpi_processor_register_performance() (which tries to read
the per_cpu(processor)) and fails to parse the data.

Reported-by-and-Tested-by: Stefan Bader <stefan.bader@canonical.com>
Suggested-by: Boris Ostrovsky <boris.ostrovsky@amd.com>
[v2: Bit-shift APIC ID by 24 bits]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

parent a7a97c63

arch/x86/xen/enlighten.c

+34 −1

Original line number	Diff line number	Diff line
		@@ -809,9 +809,40 @@ static void xen_io_delay(void)
		}

		#ifdef CONFIG_X86_LOCAL_APIC
		static unsigned long xen_set_apic_id(unsigned int x)
		{
		WARN_ON(1);
		return x;
		}
		static unsigned int xen_get_apic_id(unsigned long x)
		{
		return ((x)>>24) & 0xFFu;
		}
		static u32 xen_apic_read(u32 reg)
		{
		struct xen_platform_op op = {
		.cmd = XENPF_get_cpuinfo,
		.interface_version = XENPF_INTERFACE_VERSION,
		.u.pcpu_info.xen_cpuid = 0,
		};
		int ret = 0;

		/* Shouldn't need this as APIC is turned off for PV, and we only
		* get called on the bootup processor. But just in case. */
		if (!xen_initial_domain() \|\| smp_processor_id())
		return 0;

		if (reg == APIC_LVR)
		return 0x10;

		if (reg != APIC_ID)
		return 0;

		ret = HYPERVISOR_dom0_op(&op);
		if (ret)
		return 0;

		return op.u.pcpu_info.apic_id << 24;
		}

		static void xen_apic_write(u32 reg, u32 val)
		@@ -849,6 +880,8 @@ static void set_xen_basic_apic_ops(void)
		apic->icr_write = xen_apic_icr_write;
		apic->wait_icr_idle = xen_apic_wait_icr_idle;
		apic->safe_wait_icr_idle = xen_safe_apic_wait_icr_idle;
		apic->set_apic_id = xen_set_apic_id;
		apic->get_apic_id = xen_get_apic_id;
		}

		#endif

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