linux-kernel - [PATCH 05/10] Drivers: hv: vmbus: Handle auto EOI quirk inline

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Message-Id: <1611779025-21503-6-git-send-email-mikelley@microsoft.com>
Date:   Wed, 27 Jan 2021 12:23:40 -0800
From:   Michael Kelley <mikelley@...rosoft.com>
To:     sthemmin@...rosoft.com, kys@...rosoft.com, wei.liu@...nel.org,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, hpa@...or.com,
        daniel.lezcano@...aro.org, arnd@...db.de,
        linux-hyperv@...r.kernel.org
Cc:     mikelley@...rosoft.com, linux-kernel@...r.kernel.org,
        x86@...nel.org, linux-arch@...r.kernel.org
Subject: [PATCH 05/10] Drivers: hv: vmbus: Handle auto EOI quirk inline

On x86/x64, Hyper-V provides a flag to indicate auto EOI functionality,
but it doesn't on ARM64. Handle this quirk inline instead of calling
into code under arch/x86 (and coming, under arch/arm64).

No functional change.

Signed-off-by: Michael Kelley <mikelley@...rosoft.com>
---
 arch/x86/include/asm/mshyperv.h |  3 ---
 drivers/hv/hv.c                 | 12 +++++++++++-
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index eba637d1..d12a188 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -27,9 +27,6 @@ static inline u64 hv_get_register(unsigned int reg)
 	return value;
 }
 
-#define hv_recommend_using_aeoi() \
-	(!(ms_hyperv.hints & HV_DEPRECATING_AEOI_RECOMMENDED))
-
 #define hv_set_clocksource_vdso(val) \
 	((val).vdso_clock_mode = VDSO_CLOCKMODE_HVCLOCK)
 #define hv_enable_vdso_clocksource() \
diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
index 0c1fa69..afe7a62 100644
--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -219,7 +219,17 @@ void hv_synic_enable_regs(unsigned int cpu)
 
 	shared_sint.vector = hv_get_vector();
 	shared_sint.masked = false;
-	shared_sint.auto_eoi = hv_recommend_using_aeoi();
+
+	/*
+	 * On architectures where Hyper-V doesn't support AEOI (e.g., ARM64),
+	 * it doesn't provide a recommendation flag and AEOI must be disabled.
+	 */
+#ifdef HV_DEPRECATING_AEOI_RECOMMENDED
+	shared_sint.auto_eoi =
+			!(ms_hyperv.hints & HV_DEPRECATING_AEOI_RECOMMENDED);
+#else
+	shared_sint.auto_eoi = 0;
+#endif
 	hv_set_register(HV_REGISTER_SINT0 + VMBUS_MESSAGE_SINT,
 				shared_sint.as_uint64);
 
-- 
1.8.3.1