[v1] x86/acrn: Set up timekeeping

[PATCH] x86/acrn: Set up timekeeping

Posted by Fei Li 3 years, 8 months ago

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@intel.com>
Reviewed-by: Conghui <conghui.chen@intel.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

Re: [PATCH] x86/acrn: Set up timekeeping

Posted by Dave Hansen 3 years, 7 months ago

On 8/3/22 22:59, Fei Li wrote:
> +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;
>  }

Could you take a sec and consider what 'static inline' does and means
and also what setting:

	x86_platform.calibrate_cpu = acrn_get_tsc_khz;

does?

Using 'static inline' might compile, but it doesn't make sense.

RE: [PATCH] x86/acrn: Set up timekeeping

Posted by Li, Fei1 3 years, 7 months ago

> On 8/3/22 22:59, Fei Li wrote:
> > +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;
> >  }
>
> Could you take a sec and consider what 'static inline' does and means and also what setting:
>
>       x86_platform.calibrate_cpu = acrn_get_tsc_khz;
>
> does?
>
> Using 'static inline' might compile, but it doesn't make sense.
>
Hi Dave

Thanks for your reply.
Yes, 'inline' doesn't make sense here.
Now this commit has been merged into the x86/platform branch of tip,
I will send a patch to remove 'inline' once this commit has been merged
into the master branch.

Thanks again.

[tip: x86/platform] x86/acrn: Set up timekeeping

Posted by tip-bot2 for Fei Li 3 years, 8 months ago

The following commit has been merged into the x86/platform branch of tip:

Commit-ID:     81a71f51b89e84f39df2a3b1daf4274ae6b7b194
Gitweb:        https://git.kernel.org/tip/81a71f51b89e84f39df2a3b1daf4274ae6b7b194
Author:        Fei Li <fei1.li@intel.com>
AuthorDate:    Thu, 04 Aug 2022 13:59:03 +08:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Thu, 04 Aug 2022 11:11:59 +02:00

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@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Conghui <conghui.chen@intel.com>
Link: https://lore.kernel.org/r/20220804055903.365211-1-fei1.li@intel.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 e003a01..1dd1438 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 23f5f27..485441b 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)