linux-kernel - [PATCH] x86/acrn: Set up timekeeping

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Date:   Thu,  4 Aug 2022 13:59:03 +0800
From:   Fei Li <fei1.li@...el.com>
To:     linux-kernel@...r.kernel.org, x86@...nel.org
Cc:     gregkh@...uxfoundation.org, tglx@...utronix.de, mingo@...hat.com,
        bp@...en8.de, dave.hansen@...ux.intel.com, hpa@...or.com,
        yu1.wang@...el.com, conghui.chen@...el.com, fei1.li@...el.com
Subject: [PATCH] x86/acrn: Set up timekeeping

ACRN Hypervisor reports timing information via CPUID leaf 0x40000010.
Get the TSC and CPU frequency via CPUID leaf 0x40000010 and set the
kernel values accordingly.

Signed-off-by: Fei Li <fei1.li@...el.com>
Reviewed-by: Conghui <conghui.chen@...el.com>
---
 arch/x86/include/asm/acrn.h | 14 ++++++++++++++
 arch/x86/kernel/cpu/acrn.c  |  3 +++
 2 files changed, 17 insertions(+)

diff --git a/arch/x86/include/asm/acrn.h b/arch/x86/include/asm/acrn.h
index e003a01b7c67..1dd14381bcb6 100644
--- a/arch/x86/include/asm/acrn.h
+++ b/arch/x86/include/asm/acrn.h
@@ -10,6 +10,15 @@
 /* Bit 0 indicates whether guest VM is privileged */
 #define	ACRN_FEATURE_PRIVILEGED_VM	BIT(0)
 
+/*
+ * Timing Information.
+ * This leaf returns the current TSC frequency in kHz.
+ *
+ * EAX: (Virtual) TSC frequency in kHz.
+ * EBX, ECX, EDX: RESERVED (reserved fields are set to zero).
+ */
+#define ACRN_CPUID_TIMING_INFO		0x40000010
+
 void acrn_setup_intr_handler(void (*handler)(void));
 void acrn_remove_intr_handler(void);
 
@@ -21,6 +30,11 @@ static inline u32 acrn_cpuid_base(void)
 	return 0;
 }
 
+static inline unsigned long acrn_get_tsc_khz(void)
+{
+	return cpuid_eax(ACRN_CPUID_TIMING_INFO);
+}
+
 /*
  * Hypercalls for ACRN
  *
diff --git a/arch/x86/kernel/cpu/acrn.c b/arch/x86/kernel/cpu/acrn.c
index 23f5f27b5a02..485441b7f030 100644
--- a/arch/x86/kernel/cpu/acrn.c
+++ b/arch/x86/kernel/cpu/acrn.c
@@ -28,6 +28,9 @@ static void __init acrn_init_platform(void)
 {
 	/* Setup the IDT for ACRN hypervisor callback */
 	alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, asm_sysvec_acrn_hv_callback);
+
+	x86_platform.calibrate_tsc = acrn_get_tsc_khz;
+	x86_platform.calibrate_cpu = acrn_get_tsc_khz;
 }
 
 static bool acrn_x2apic_available(void)

base-commit: e0dccc3b76fb35bb257b4118367a883073d7390e
-- 
2.34.1