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Date: Thu, 7 Feb 2013 10:53:02 -0800 From: Yinghai Lu <yinghai@...nel.org> To: Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>, "H. Peter Anvin" <hpa@...or.com> Cc: linux-kernel@...r.kernel.org, Stoney Wang <song-bo.wang@...com>, Yinghai Lu <yinghai@...nel.org>, stable@...nel.org Subject: [PATCH v4] x86, apic: Check fadt x2apic phys in x2apic_phys_probe() From: Stoney Wang <song-bo.wang@...com> When a HP ProLiant DL980 G7 Server boots a regular kernel, there will be intermittent lost interrupts which could result in a hang or (in extreme cases) data loss. The reason is that this system only supports x2apic physical mode, while the kernel boots with a logical-cluster default setting. This bug can be worked around by specifying "x2apic_phys" or "nox2apic" boot option, but we want to handle this system without requiring manual workarounds. BIOS set ACPI_FADT_APIC_PHYSICAL in FADT table. As all apicids are less than 255, BIOS need to pass the control to the OS with xapic mode, according to x2apic-spec, chapter 2.9. Current code handle x2apic when BIOS pass with xapic mode: When user specify x2apic_phys, or FADT indicates PHYSICAL. 1. During madt oem check, apic driver is set with xapic logical or xapic phys driver at first. 2. enable_IR_x2apic() will enable x2apic_mode. 3. if user specify x2apic_phys, x2apic_phys_probe() will install right x2apic phys driver and use x2apic phys mode. otherwise will skip and let x2apic_cluster_probe to take over to install x2apic cluster driver (wrong one) even FADT indicates PHYSICAL, because x2apic_phys_probe does not check FADT PHYSICAL. Add checking x2apic_fadt_phys in x2apic_phys_probe() to fix the problem. -v3: update the change according to Ingo. -v4: merge changelog from Ingo. [ changelog, and simplify code - Yinghai Lu ] Signed-off-by: Stoney Wang <song-bo.wang@...com> Signed-off-by: Yinghai Lu <yinghai@...nel.org> Cc: stable@...nel.org --- arch/x86/kernel/apic/x2apic_phys.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-) Index: linux-2.6/arch/x86/kernel/apic/x2apic_phys.c =================================================================== --- linux-2.6.orig/arch/x86/kernel/apic/x2apic_phys.c +++ linux-2.6/arch/x86/kernel/apic/x2apic_phys.c @@ -20,18 +20,19 @@ static int set_x2apic_phys_mode(char *ar } early_param("x2apic_phys", set_x2apic_phys_mode); -static int x2apic_acpi_madt_oem_check(char *oem_id, char *oem_table_id) +static bool x2apic_fadt_phys(void) { - if (x2apic_phys) - return x2apic_enabled(); - else if ((acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID) && - (acpi_gbl_FADT.flags & ACPI_FADT_APIC_PHYSICAL) && - x2apic_enabled()) { + if ((acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID) && + (acpi_gbl_FADT.flags & ACPI_FADT_APIC_PHYSICAL)) { printk(KERN_DEBUG "System requires x2apic physical mode\n"); - return 1; + return true; } - else - return 0; + return false; +} + +static int x2apic_acpi_madt_oem_check(char *oem_id, char *oem_table_id) +{ + return x2apic_enabled() && (x2apic_phys || x2apic_fadt_phys()); } static void @@ -82,7 +83,7 @@ static void init_x2apic_ldr(void) static int x2apic_phys_probe(void) { - if (x2apic_mode && x2apic_phys) + if (x2apic_mode && (x2apic_phys || x2apic_fadt_phys())) return 1; return apic == &apic_x2apic_phys; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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