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Subject[PATCH 1/3] x86/Hyper-V: Set x2apic destination mode to physical when x2apic is available
Date
From: Lan Tianyu <Tianyu.Lan@microsoft.com>

Hyper-V doesn't provide irq remapping for IO-APIC. To enable x2apic,
set x2apic destination mode to physcial mode when x2apic is available
and Hyper-V IOMMU driver makes sure cpus assigned with IO-APIC irqs have
8-bit APIC id.

Signed-off-by: Lan Tianyu <Tianyu.Lan@microsoft.com>
---
arch/x86/kernel/cpu/mshyperv.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)

diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index e81a2db..9d62f33 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -36,6 +36,8 @@
struct ms_hyperv_info ms_hyperv;
EXPORT_SYMBOL_GPL(ms_hyperv);

+extern int x2apic_phys;
+
#if IS_ENABLED(CONFIG_HYPERV)
static void (*vmbus_handler)(void);
static void (*hv_stimer0_handler)(void);
@@ -328,6 +330,18 @@ static void __init ms_hyperv_init_platform(void)
# ifdef CONFIG_SMP
smp_ops.smp_prepare_boot_cpu = hv_smp_prepare_boot_cpu;
# endif
+
+/*
+ * Hyper-V doesn't provide irq remapping for IO-APIC. To enable x2apic,
+ * set x2apic destination mode to physcial mode when x2apic is available
+ * and Hyper-V IOMMU driver makes sure cpus assigned with IO-APIC irqs
+ * have 8-bit APIC id.
+ */
+# if IS_ENABLED(CONFIG_HYPERV_IOMMU)
+ if (x2apic_supported())
+ x2apic_phys = 1;
+# endif
+
#endif
}

--
2.7.4
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