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Message-Id: <1300802807-7742-1-git-send-email-youquan.song@intel.com>
Date: Tue, 22 Mar 2011 22:06:47 +0800
From: Youquan Song <youquan.song@...el.com>
To: linux-kernel@...r.kernel.org, hpa@...ux.intel.com,
david.woodhouse@...el.com
Cc: suresh.b.siddha@...el.com, allen.m.kay@...el.com,
kent.liu@...el.com, Youquan Song <youquan.song@...ux.intel.com>,
Youquan Song <youquan.song@...el.com>
Subject: [PATCH] enable x2apic opt out
New version of VT-d2 specification includes a new feature that provide firmware
a way to request system software to opt out of enable x2APIC mode.
DMAR ACPI table newly define flags.1 bit: x2APIC_OPT_OUT which is set to request
System software opt out xAPIC mode if flags.0 bit:INTR_REMAP is also set.
This patch enable the feature. Also re-define x2apic_supported() to address
platform x2apic support needs 1)processor has x2apic capability 2)interrupt
remapping support 3)firmware does not request opt-out.
Signed-off-by: Youquan Song <youquan.song@...el.com>
---
arch/x86/include/asm/apic.h | 2 --
arch/x86/kernel/apic/apic.c | 13 +++++++++----
drivers/pci/dmar.c | 28 ++++++++++++++++++++++++++--
include/linux/dmar.h | 3 +++
include/linux/intel-iommu.h | 4 ++++
5 files changed, 42 insertions(+), 8 deletions(-)
diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index 3c89694..aa3fc82 100644
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -192,7 +192,6 @@ static inline int x2apic_enabled(void)
return 0;
}
-#define x2apic_supported() (cpu_has_x2apic)
static inline void x2apic_force_phys(void)
{
x2apic_phys = 1;
@@ -213,7 +212,6 @@ static inline void x2apic_force_phys(void)
}
#define x2apic_preenabled 0
-#define x2apic_supported() 0
#endif
extern void enable_IR_x2apic(void);
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 76b96d7..6c96c45 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1449,11 +1449,11 @@ void __init enable_IR_x2apic(void)
{
unsigned long flags;
struct IO_APIC_route_entry **ioapic_entries = NULL;
- int ret, x2apic_enabled = 0;
+ int ret = 0, x2apic_enabled = 0;
int dmar_table_init_ret;
dmar_table_init_ret = dmar_table_init();
- if (dmar_table_init_ret && !x2apic_supported())
+ if (dmar_table_init_ret && !cpu_has_x2apic)
return;
ioapic_entries = alloc_ioapic_entries();
@@ -1465,6 +1465,7 @@ void __init enable_IR_x2apic(void)
ret = save_IO_APIC_setup(ioapic_entries);
if (ret) {
pr_info("Saving IO-APIC state failed: %d\n", ret);
+ ret = 0;
goto out;
}
@@ -1491,7 +1492,8 @@ void __init enable_IR_x2apic(void)
x2apic_force_phys();
}
- x2apic_enabled = 1;
+ if (x2apic_supported())
+ x2apic_enabled = 1;
if (x2apic_supported() && !x2apic_mode) {
x2apic_mode = 1;
@@ -1514,8 +1516,11 @@ out:
if (x2apic_preenabled)
panic("x2apic: enabled by BIOS but kernel init failed.");
- else if (cpu_has_x2apic)
+ else if (!ret && cpu_has_x2apic) /* IR enabling failed */
pr_info("Not enabling x2apic, Intr-remapping init failed.\n");
+ else if (!x2apic_supported() && cpu_has_x2apic)
+ pr_info("Not enabling x2apic, firmware requests OS opt-out "
+ "x2apic.\n");
}
#ifdef CONFIG_X86_64
diff --git a/drivers/pci/dmar.c b/drivers/pci/dmar.c
index 09933eb..a35dca9 100644
--- a/drivers/pci/dmar.c
+++ b/drivers/pci/dmar.c
@@ -705,7 +705,7 @@ int __init detect_intel_iommu(void)
* is added, we will not need this any more.
*/
dmar = (struct acpi_table_dmar *) dmar_tbl;
- if (ret && cpu_has_x2apic && dmar->flags & 0x1)
+ if (ret && x2apic_supported() && dmar->flags & DMAR_INTR_REMAP)
printk(KERN_INFO
"Queued invalidation will be enabled to support "
"x2apic and Intr-remapping.\n");
@@ -1461,6 +1461,30 @@ int __init dmar_ir_support(void)
dmar = (struct acpi_table_dmar *)dmar_tbl;
if (!dmar)
return 0;
- return dmar->flags & 0x1;
+ return dmar->flags & DMAR_INTR_REMAP;
}
+
+/*
+ * Check if the platform support x2apic
+ * three necessary conditions:
+ * a. processor support x2apic
+ * b. interrupt remapping support
+ * c. when interrupt reamapping support,bit of x2APIC_OPT_OUT at "DMAR flags"
+ * is not set which means firmware does not tell OS opt out x2apic
+ */
+int __init x2apic_supported(void)
+{
+ struct acpi_table_dmar *dmar;
+ unsigned int flags = 0;
+
+ if (!cpu_has_x2apic)
+ return 0;
+
+ dmar = (struct acpi_table_dmar *)dmar_tbl;
+ if (!dmar)
+ return 0;
+ flags = DMAR_INTR_REMAP | DMAR_X2APIC_OPT_OUT;
+ return ((dmar->flags & flags) == DMAR_INTR_REMAP);
+}
+
IOMMU_INIT_POST(detect_intel_iommu);
diff --git a/include/linux/dmar.h b/include/linux/dmar.h
index 7b776d7..73c9bff 100644
--- a/include/linux/dmar.h
+++ b/include/linux/dmar.h
@@ -228,8 +228,11 @@ struct dmar_atsr_unit {
};
extern int intel_iommu_init(void);
+extern int x2apic_supported(void);
+
#else /* !CONFIG_DMAR: */
static inline int intel_iommu_init(void) { return -ENODEV; }
+static inline int x2apic_supported(void) { return 0; }
#endif /* CONFIG_DMAR */
#endif /* __DMAR_H__ */
diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
index 9310c69..2d086e5 100644
--- a/include/linux/intel-iommu.h
+++ b/include/linux/intel-iommu.h
@@ -29,6 +29,10 @@
#include <asm/cacheflush.h>
#include <asm/iommu.h>
+/* DMAR Flags bits */
+#define DMAR_INTR_REMAP 0x1
+#define DMAR_X2APIC_OPT_OUT 0x2
+
/*
* Intel IOMMU register specification per version 1.0 public spec.
*/
--
1.6.4.2
--
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