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Subject[PATCH v1 1/2] x86/hyperv: get spinlock retry number on Hyper-V
Date
EBX of Implementation Recommendations MSR (0x40000004) indicates
recommended number of attempts to retry a spinlock failure before
notifying the hypervisor about the failures.

0xFFFFFFFF indicates never to retry.

Signed-off-by: Yi Sun <yi.y.sun@linux.intel.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Michael Kelley (EOSG) <Michael.H.Kelley@microsoft.com>
Cc: Juergen Gross <jgross@suse.com>
---
arch/x86/include/asm/mshyperv.h | 3 +++
arch/x86/kernel/cpu/mshyperv.c | 1 +
2 files changed, 4 insertions(+)

diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index 0d6271c..f909365 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -11,10 +11,13 @@

#define VP_INVAL U32_MAX

+#define HYPERV_SPINLOCK_RETRY_NEVER U32_MAX
+
struct ms_hyperv_info {
u32 features;
u32 misc_features;
u32 hints;
+ u32 num_spin_retry;
u32 nested_features;
u32 max_vp_index;
u32 max_lp_index;
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 1c72f38..04f480a 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -222,6 +222,7 @@ static void __init ms_hyperv_init_platform(void)
ms_hyperv.features = cpuid_eax(HYPERV_CPUID_FEATURES);
ms_hyperv.misc_features = cpuid_edx(HYPERV_CPUID_FEATURES);
ms_hyperv.hints = cpuid_eax(HYPERV_CPUID_ENLIGHTMENT_INFO);
+ ms_hyperv.num_spin_retry = cpuid_ebx(HYPERV_CPUID_ENLIGHTMENT_INFO);

pr_info("Hyper-V: features 0x%x, hints 0x%x\n",
ms_hyperv.features, ms_hyperv.hints);
--
1.9.1
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