On Monday, October 27, 2014 05:58:10 PM Hanjun Guo wrote:
On 2014-10-25 1:39, Lorenzo Pieralisi wrote:
On Fri, Oct 17, 2014 at 02:37:08PM +0100, Hanjun Guo wrote:
Introduce a new function map_gicc_mpidr() to allow MPIDRs to be obtained from the GICC Structure introduced by ACPI 5.1.
MPIDR is the CPU hardware ID as local APIC ID on x86 platform, so we use MPIDR not the GIC CPU interface ID to identify CPUs.
Signed-off-by: Hanjun Guo hanjun.guo@linaro.org
arch/arm64/include/asm/acpi.h | 29 +++++++++++++++++++++++++++++ arch/arm64/kernel/acpi.c | 1 - drivers/acpi/processor_core.c | 37 +++++++++++++++++++++++++++++++++++++ 3 files changed, 66 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h index c82d4a1..483ff45 100644 --- a/arch/arm64/include/asm/acpi.h +++ b/arch/arm64/include/asm/acpi.h @@ -12,6 +12,8 @@ #ifndef _ASM_ACPI_H #define _ASM_ACPI_H +#include <asm/smp_plat.h>
/* Basic configuration for ACPI */ #ifdef CONFIG_ACPI #define acpi_strict 1 /* No out-of-spec workarounds on ARM64 */ @@ -45,6 +47,33 @@ static inline void enable_acpi(void) acpi_noirq = 0; } +/* MPIDR value provided in GICC structure is 64 bits, but the
- existing apic_id (CPU hardware ID) using in acpi processor
- driver is 32-bit, to conform to the same datatype we need
- to repack the GICC structure MPIDR.
- Only 32 bits of MPIDR are used:
- Bits [0:7] Aff0;
- Bits [8:15] Aff1;
- Bits [16:23] Aff2;
- Bits [32:39] Aff3;
- */
+static inline u32 pack_mpidr(u64 mpidr) +{
- return (u32) ((mpidr & 0xff00000000) >> 8) | mpidr;
+}
+/*
- The ACPI processor driver for ACPI core code needs this macro
- to find out this cpu was already mapped (mapping from CPU hardware
- ID to CPU logical ID) or not.
- cpu_logical_map(cpu) is the mapping of MPIDR and the logical cpu,
- and MPIDR is the cpu hardware ID we needed to pack.
- */
+#define cpu_physical_id(cpu) pack_mpidr(cpu_logical_map(cpu))
/*
- It's used from ACPI core in kdump to boot UP system with SMP kernel,
- with this check the ACPI core will not override the CPU index
diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c index 34837e0..e91ec76 100644 --- a/arch/arm64/kernel/acpi.c +++ b/arch/arm64/kernel/acpi.c @@ -24,7 +24,6 @@ #include <linux/bootmem.h> #include <linux/smp.h> -#include <asm/smp_plat.h> #include <asm/cputype.h> #include <asm/cpu_ops.h> diff --git a/drivers/acpi/processor_core.c b/drivers/acpi/processor_core.c index e32321c..4007313 100644 --- a/drivers/acpi/processor_core.c +++ b/drivers/acpi/processor_core.c @@ -64,6 +64,38 @@ static int map_lsapic_id(struct acpi_subtable_header *entry, return 0; } +/*
- On ARM platform, MPIDR value is the hardware ID as apic ID
- on Intel platforms
- */
+static int map_gicc_mpidr(struct acpi_subtable_header *entry,
int device_declaration, u32 acpi_id, int *mpidr)+{
- struct acpi_madt_generic_interrupt *gicc =
container_of(entry, struct acpi_madt_generic_interrupt, header);- if (!(gicc->flags & ACPI_MADT_ENABLED))
return -ENODEV;- /* In the GIC interrupt model, logical processors are
* required to have a Processor Device object in the DSDT,* so we should check device_declaration here*/- if (device_declaration && (gicc->uid == acpi_id)) {
/** Only bits [0:7] Aff0, bits [8:15] Aff1, bits [16:23] Aff2* and bits [32:39] Aff3 are meaningful, so pack the Affx* fields into a single 32 bit identifier to accommodate the* acpi processor drivers.*/*mpidr = ((gicc->arm_mpidr & 0xff00000000) >> 8)| gicc->arm_mpidr;The simple fact that you define a function to pack the mpidr value and you can't use it here because this is *generic* code is telling, and a very bad omen. At the cost of sounding like a broken record, I do not like this mpidr->apic->logical_cpu song and dance at all. ACPI is peppered with code (eg hotplug is another example, CPUidle driver even worse) that is supposed to be generic but contains x86 code to carry out this cpuid conversion, I really think that in order to start an ARM64 ACPI port properly we should at least try to factor out this physical to logical cpu id conversion, and it is not the first time that I mention this on the lists.
I know, thanks for pointing this out. As I replied in previous version of this patch set, apic_id is x86/ia64 specific, but the meaning behind it is not. It means the CPU hardware id to identify itself in the system, it just like MPIDR on ARM.
I will send out a patch for RFC to convert apic_id to physid which is generic for all platforms.
I will also talk to Rafael about this at the earliest opportunity, I guess that x86 code relies on apic-id because some ACPI versions could not rely on the acpi-id or some other reasons I have to investigate.
As ACPI spec (section 8.4, Declaring Processors) said, Each processor in the system must be declared in the ACPI namespace, so each cpu will have acpi_id in all ACPI versions, and in theory we can map acpi_id to logical cpu id if we want to.
But things are complicated, apic_id is connected to many tables, MADT for smp init, DSDT for device driver, and SRAT for NUMA (there is no acpi_id in it, ONLY has apic_id in the table for x86/ia64), so if we want to factor the code to map acpi_id to logical cpu id, we need to modify:
- ACPI drivers;
- SMP init for x86 and ia64
- the mappings for NUMA init for x86 and ia64
that will be lots of work I think.
And error prone for that matter.