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authorSuresh Siddha <suresh.b.siddha@intel.com>2011-08-23 20:05:18 -0400
committerIngo Molnar <mingo@elte.hu>2011-09-21 04:21:50 -0400
commit41750d31fc9599fd81763e685a6b7b42d298c4f8 (patch)
tree6cacc746aa159c8bd08f151270f0bffe126caa9d /include/linux/dmar.h
parent9d037a777695993ec7437e5f451647dea7919d4c (diff)
x86, x2apic: Enable the bios request for x2apic optout
On the platforms which are x2apic and interrupt-remapping capable, Linux kernel is enabling x2apic even if the BIOS doesn't. This is to take advantage of the features that x2apic brings in. Some of the OEM platforms are running into issues because of this, as their bios is not x2apic aware. For example, this was resulting in interrupt migration issues on one of the platforms. Also if the BIOS SMI handling uses APIC interface to send SMI's, then the BIOS need to be aware of x2apic mode that OS has enabled. On some of these platforms, BIOS doesn't have a HW mechanism to turnoff the x2apic feature to prevent OS from enabling it. To resolve this mess, recent changes to the VT-d2 specification: http://download.intel.com/technology/computing/vptech/Intel(r)_VT_for_Direct_IO.pdf includes a mechanism that provides BIOS a way to request system software to opt out of enabling x2apic mode. Look at the x2apic optout flag in the DMAR tables before enabling the x2apic mode in the platform. Also print a warning that we have disabled x2apic based on the BIOS request. Kernel boot parameter "intremap=no_x2apic_optout" can be used to override the BIOS x2apic optout request. Signed-off-by: Youquan Song <youquan.song@intel.com> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Cc: yinghai@kernel.org Cc: joerg.roedel@amd.com Cc: tony.luck@intel.com Cc: dwmw2@infradead.org Link: http://lkml.kernel.org/r/20110824001456.171766616@sbsiddha-desk.sc.intel.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'include/linux/dmar.h')
-rw-r--r--include/linux/dmar.h14
1 files changed, 12 insertions, 2 deletions
diff --git a/include/linux/dmar.h b/include/linux/dmar.h
index 7b776d71d36d..2dc810e35dd0 100644
--- a/include/linux/dmar.h
+++ b/include/linux/dmar.h
@@ -26,8 +26,13 @@
26#include <linux/msi.h> 26#include <linux/msi.h>
27#include <linux/irqreturn.h> 27#include <linux/irqreturn.h>
28 28
29/* DMAR Flags */
30#define DMAR_INTR_REMAP 0x1
31#define DMAR_X2APIC_OPT_OUT 0x2
32
29struct intel_iommu; 33struct intel_iommu;
30#if defined(CONFIG_DMAR) || defined(CONFIG_INTR_REMAP) 34#if defined(CONFIG_DMAR) || defined(CONFIG_INTR_REMAP)
35extern struct acpi_table_header *dmar_tbl;
31struct dmar_drhd_unit { 36struct dmar_drhd_unit {
32 struct list_head list; /* list of drhd units */ 37 struct list_head list; /* list of drhd units */
33 struct acpi_dmar_header *hdr; /* ACPI header */ 38 struct acpi_dmar_header *hdr; /* ACPI header */
@@ -110,7 +115,7 @@ struct irte {
110#ifdef CONFIG_INTR_REMAP 115#ifdef CONFIG_INTR_REMAP
111extern int intr_remapping_enabled; 116extern int intr_remapping_enabled;
112extern int intr_remapping_supported(void); 117extern int intr_remapping_supported(void);
113extern int enable_intr_remapping(int); 118extern int enable_intr_remapping(void);
114extern void disable_intr_remapping(void); 119extern void disable_intr_remapping(void);
115extern int reenable_intr_remapping(int); 120extern int reenable_intr_remapping(int);
116 121
@@ -177,7 +182,7 @@ static inline int set_msi_sid(struct irte *irte, struct pci_dev *dev)
177 182
178#define intr_remapping_enabled (0) 183#define intr_remapping_enabled (0)
179 184
180static inline int enable_intr_remapping(int eim) 185static inline int enable_intr_remapping(void)
181{ 186{
182 return -1; 187 return -1;
183} 188}
@@ -192,6 +197,11 @@ static inline int reenable_intr_remapping(int eim)
192} 197}
193#endif 198#endif
194 199
200enum {
201 IRQ_REMAP_XAPIC_MODE,
202 IRQ_REMAP_X2APIC_MODE,
203};
204
195/* Can't use the common MSI interrupt functions 205/* Can't use the common MSI interrupt functions
196 * since DMAR is not a pci device 206 * since DMAR is not a pci device
197 */ 207 */