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Date: Fri, 16 Jan 2015 16:07:26 +0800
From: Jiang Liu <jiang.liu@...ux.intel.com>
To: Thomas Gleixner <tglx@...utronix.de>,
LKML <linux-kernel@...r.kernel.org>
CC: Joerg Roedel <joro@...tes.org>, x86@...nel.org,
Tony Luck <tony.luck@...el.com>, Borislav Petkov <bp@...en8.de>
Subject: Re: [patch 06/23] x86/apic: Check x2apic early
Hi Thomas,
check_x2apic() is a little too early. If system panics
in check_x2apic(), it's a blank console if system panics in
check_x2apic().
I also tried to disabled x2apic in check_x2apic() if
x2apic is enabled by BIOS but kernel doesn't support x2apic.
It may continue for a while, but eventually run into livelock
with following log messages:
[ 222.436829] dmar: INTR-REMAP: Request device [[f0:1f.7] fault index 2
[ 222.436829] INTR-REMAP:[fault reason 36] Detected reserved fields in
the IRTE entry
[ 222.452737] dmar: INTR-REMAP: Request device [[f0:1f.7] fault index 2
[ 222.452737] INTR-REMAP:[fault reason 36] Detected reserved fields in
the IRTE entry
[ 222.468645] dmar: INTR-REMAP: Request device [[f0:1f.7] fault index 2
[ 222.468645] INTR-REMAP:[fault reason 36] Detected reserved fields in
the IRTE entry
[ 222.484554] dmar: INTR-REMAP: Request device [[f0:1f.7] fault index 2
[ 222.484554] INTR-REMAP:[fault reason 36] Detected reserved fields in
the IRTE entry
[ 222.500463] dmar: INTR-REMAP: Request device [[f0:1f.7] fault index 2
[ 222.500463] INTR-REMAP:[fault reason 36] Detected reserved fields in
the IRTE entry
[ 222.516371] dmar: INTR-REMAP: Request device [[f0:1f.7] fault index 2
[ 222.516371] INTR-REMAP:[fault reason 36] Detected reserved fields in
the IRTE entry
[ 222.532285] dmar: INTR-REMAP: Request device [[f0:1f.7] fault index 2
[ 222.532285] INTR-REMAP:[fault reason 36] Detected reserved fields in
the IRTE entry
[ 222.548200] dmar: INTR-REMAP: Request device [[f0:1f.7] fault index 2
So seems we need to revert to original solution.
Thanks!
Gerry
------------------------------------------------------------------------
On 2015/1/16 5:22, Thomas Gleixner wrote:
No point in delaying the x2apic detection for the CONFIG_X86_X2APIC=n
case to enable_IR_x2apic(). We rather detect that in the early boot
code in check_x2apic().
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
arch/x86/include/asm/apic.h | 6 ++----
arch/x86/kernel/apic/apic.c | 33 +++++++++++++++++++--------------
2 files changed, 21 insertions(+), 18 deletions(-)
Index: tip/arch/x86/include/asm/apic.h
===================================================================
--- tip.orig/arch/x86/include/asm/apic.h
+++ tip/arch/x86/include/asm/apic.h
@@ -177,7 +177,6 @@ static inline u64 native_x2apic_icr_read
extern int x2apic_mode;
extern int x2apic_phys;
-extern void check_x2apic(void);
extern void enable_x2apic(void);
static inline int x2apic_enabled(void)
{
@@ -193,9 +192,6 @@ static inline void x2apic_force_phys(voi
static inline void disable_x2apic(void)
{
}
-static inline void check_x2apic(void)
-{
-}
static inline void enable_x2apic(void)
{
}
@@ -429,6 +425,7 @@ static inline u32 safe_apic_wait_icr_idl
}
extern void __init apic_set_eoi_write(void (*eoi_write)(u32 reg, u32 v));
+extern void __init check_x2apic(void);
#else /* CONFIG_X86_LOCAL_APIC */
@@ -440,6 +437,7 @@ static inline void apic_icr_write(u32 lo
static inline void apic_wait_icr_idle(void) { }
static inline u32 safe_apic_wait_icr_idle(void) { return 0; }
static inline void apic_set_eoi_write(void (*eoi_write)(u32 reg, u32 v)) {}
+static inline void check_x2apic(void) { }
#endif /* CONFIG_X86_LOCAL_APIC */
Index: tip/arch/x86/kernel/apic/apic.c
===================================================================
--- tip.orig/arch/x86/kernel/apic/apic.c
+++ tip/arch/x86/kernel/apic/apic.c
@@ -1541,14 +1541,6 @@ static __init void disable_x2apic(void)
x2apic_disabled = 1;
}
-void check_x2apic(void)
-{
- if (x2apic_enabled()) {
- pr_info("x2apic enabled by BIOS, switching to x2apic ops\n");
- x2apic_mode = 1;
- }
-}
-
void enable_x2apic(void)
{
u64 msr;
@@ -1568,7 +1560,25 @@ void enable_x2apic(void)
wrmsrl(MSR_IA32_APICBASE, msr | X2APIC_ENABLE);
}
}
-#endif /* CONFIG_X86_X2APIC */
+
+void __init check_x2apic(void)
+{
+ if (x2apic_enabled()) {
+ pr_info("x2apic enabled by BIOS, switching to x2apic ops\n");
+ x2apic_mode = 1;
+ }
+}
+#else /* CONFIG_X86_X2APIC */
+void __init check_x2apic(void)
+{
+ if (!cpu_has_apic || !apic_is_x2apic_enabled())
+ return;
+ /*
+ * Checkme: Can we simply turn off x2apic here instead of panic?
+ */
+ panic("BIOS has enabled x2apic but kernel doesn't support x2apic,
please disable x2apic in BIOS.\n");
+}
+#endif /* !CONFIG_X86_X2APIC */
static int __init try_to_enable_IR(void)
{
@@ -1620,11 +1630,6 @@ void __init enable_IR_x2apic(void)
unsigned long flags;
int ret, ir_stat;
- if (!IS_ENABLED(CONFIG_X86_X2APIC)) {
- if (apic_is_x2apic_enabled())
- panic("BIOS has enabled x2apic but kernel doesn't support x2apic,
please disable x2apic in BIOS.\n");
- }
-
ir_stat = irq_remapping_prepare();
if (ir_stat < 0 && !x2apic_supported())
return;
--
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