RongQing,

At 04/09/2018 02:38 PM, Li,Rongqing wrote:


-----邮件原件-----
发件人: Dou Liyang [mailto:douly.f...@cn.fujitsu.com]
发送时间: 2018年4月9日 13:38
收件人: Li,Rongqing <lirongq...@baidu.com>; linux-kernel@vger.kernel.org;
t...@linutronix.de; mi...@redhat.com; h...@zytor.com; jgr...@suse.com;
x...@kernel.org; pet...@infradead.org
主题: Re: [RFC PATCH] x86/acpi: Prevent x2apic id -1 from being accounted

Hi RongQing,

Is there an local x2apic whose ID is  in your machine?


I think no

[...]

[    0.000000] ACPI: X2APIC (apic_id[0xffffffff] uid[0x00] disabled)
[    0.000000] ACPI: X2APIC (apic_id[0xffffffff] uid[0x01] disabled)
[    0.000000] ACPI: X2APIC (apic_id[0xffffffff] uid[0x02] disabled)

Ah, sure enough!

[...]


At 04/08/2018 07:38 PM, Li RongQing wrote:
local_apic_id of acpi_madt_local_x2apic is u32, it is converted to int
when checked by default_apic_id_valid() and return true if it is
larger than 0x7fffffff, this is wrong


For x2apic enabled systems,

    - the byte length of X2APIC ID is 4, and it can be larger than
      0x7fffffff in theory


Yes

    - the ->apic_id_valid points to x2apic_apic_id_valid(), which always
      return _ture_ , not default_apic_id_valid().


To this machine, the apic is apic_flat

I see, I am sorry the title and changelog make me misunderstand.

  Here, actually, we prevent all the X2APIC Id from being parsed in
  non-x2apic mode, not just 0xFFFFFFFF. because the values of x2APIC ID
  must be 255 and greater in ACPI MADT.


-RongQing

Thanks,
        dou

and if local_apic_id is invalid, we should prevent it from being
accounted > This fixes a bug that Purley platform displays too many
possible cpu

Signed-off-by: Li RongQing <lirongq...@baidu.com>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Dou Liyang <douly.f...@cn.fujitsu.com>
---
   arch/x86/include/asm/apic.h          |  4 ++--
   arch/x86/kernel/acpi/boot.c          | 10 ++++++----
   arch/x86/kernel/apic/apic_common.c   |  2 +-
   arch/x86/kernel/apic/apic_numachip.c |  2 +-
   arch/x86/kernel/apic/x2apic.h        |  2 +-
   arch/x86/kernel/apic/x2apic_phys.c   |  2 +-
   arch/x86/kernel/apic/x2apic_uv_x.c   |  2 +-
   arch/x86/xen/apic.c                  |  2 +-
   8 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index 40a3d3642f3a..08acd954f00e 100644
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -313,7 +313,7 @@ struct apic {
        /* Probe, setup and smpboot functions */
        int     (*probe)(void);
        int     (*acpi_madt_oem_check)(char *oem_id, char
*oem_table_id);
-       int     (*apic_id_valid)(int apicid);
+       int     (*apic_id_valid)(u32 apicid);
        int     (*apic_id_registered)(void);

        bool    (*check_apicid_used)(physid_mask_t *map, int apicid);
@@ -486,7 +486,7 @@ static inline unsigned int read_apic_id(void)
        return apic->get_apic_id(reg);
   }

-extern int default_apic_id_valid(int apicid);
+extern int default_apic_id_valid(u32 apicid);
   extern int default_acpi_madt_oem_check(char *, char *);
   extern void default_setup_apic_routing(void);

diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 7a37d9357bc4..7412564dc2a7 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -200,7 +200,7 @@ acpi_parse_x2apic(struct acpi_subtable_header
*header, const unsigned long end)
   {
        struct acpi_madt_local_x2apic *processor = NULL;
   #ifdef CONFIG_X86_X2APIC
-       int apic_id;
+       u32 apic_id;
        u8 enabled;
   #endif

@@ -222,10 +222,12 @@ acpi_parse_x2apic(struct acpi_subtable_header
*header, const unsigned long end)
         * to not preallocating memory for all NR_CPUS
         * when we use CPU hotplug.
         */
-       if (!apic->apic_id_valid(apic_id) && enabled)
+       if (!apic->apic_id_valid(apic_id)) {
                printk(KERN_WARNING PREFIX "x2apic entry ignored\n");

Due to the disable APIC entries may not exist physically, please just
printk the warning if the APIC ID is enabled.

if (!apic->apic_id_valid(apic_id)) {
        if(enabled)
                printk...

        return 0;
}



Thanks,
        dou


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