[tip:x86/hyperv] x86, hyperv: Get the local APIC timer frequency from the hypervisor

[tip:x86/hyperv] x86, hyperv: Get the local APIC timer frequency from the hypervisor

[tip-bot for K. Y. Srinivasan]

Commit-ID:  9e7827b5ea4ca93b4d864bc07c0fafb838d496b1
Gitweb:     http://git.kernel.org/tip/9e7827b5ea4ca93b4d864bc07c0fafb838d496b1
Author:     K. Y. Srinivasan <kys@microsoft.com>
AuthorDate: Mon, 30 Sep 2013 17:28:52 +0200
Committer:  H. Peter Anvin <hpa@linux.intel.com>
CommitDate: Thu, 10 Oct 2013 11:44:12 -0700

x86, hyperv: Get the local APIC timer frequency from the hypervisor

Hyper-V supports a mechanism for retrieving the local APIC frequency.
Use this and bypass the calibration code in the kernel . This would
allow us to boot the Linux kernel as a "modern VM" on Hyper-V where
many of the legacy devices (such as PIT) are not emulated.

I would like to thank Olaf Hering <olaf@aepfle.de>, Jan Beulich <JBeulich@suse.com> and
H. Peter Anvin <h.peter.anvin@intel.com> for their help in this effort.

In this version of the patch, I have addressed Jan's comments.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Link: http://lkml.kernel.org/r/1380554932-9888-1-git-send-email-olaf@aepfle.de
Tested-by: Olaf Hering <olaf@aepfle.de>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
---
 arch/x86/include/uapi/asm/hyperv.h | 19 +++++++++++++++++++
 arch/x86/kernel/cpu/mshyperv.c     | 24 ++++++++++++++++++++++++
 2 files changed, 43 insertions(+)

diff --git a/arch/x86/include/uapi/asm/hyperv.h b/arch/x86/include/uapi/asm/hyperv.h
index b80420b..b8f1c01 100644
--- a/arch/x86/include/uapi/asm/hyperv.h
+++ b/arch/x86/include/uapi/asm/hyperv.h
@@ -27,6 +27,19 @@
 #define HV_X64_MSR_VP_RUNTIME_AVAILABLE		(1 << 0)
 /* Partition Reference Counter (HV_X64_MSR_TIME_REF_COUNT) available*/
 #define HV_X64_MSR_TIME_REF_COUNT_AVAILABLE	(1 << 1)
+
+/*
+ * There is a single feature flag that signifies the presence of the MSR
+ * that can be used to retrieve both the local APIC Timer frequency as
+ * well as the TSC frequency.
+ */
+
+/* Local APIC timer frequency MSR (HV_X64_MSR_APIC_FREQUENCY) is available */
+#define HV_X64_MSR_APIC_FREQUENCY_AVAILABLE (1 << 11)
+
+/* TSC frequency MSR (HV_X64_MSR_TSC_FREQUENCY) is available */
+#define HV_X64_MSR_TSC_FREQUENCY_AVAILABLE (1 << 11)
+
 /*
  * Basic SynIC MSRs (HV_X64_MSR_SCONTROL through HV_X64_MSR_EOM
  * and HV_X64_MSR_SINT0 through HV_X64_MSR_SINT15) available
@@ -136,6 +149,12 @@
 /* MSR used to read the per-partition time reference counter */
 #define HV_X64_MSR_TIME_REF_COUNT		0x40000020
 
+/* MSR used to retrieve the TSC frequency */
+#define HV_X64_MSR_TSC_FREQUENCY		0x40000022
+
+/* MSR used to retrieve the local APIC timer frequency */
+#define HV_X64_MSR_APIC_FREQUENCY		0x40000023
+
 /* Define the virtual APIC registers */
 #define HV_X64_MSR_EOI				0x40000070
 #define HV_X64_MSR_ICR				0x40000071
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 71a39f3..0a490ca 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -15,6 +15,7 @@
 #include <linux/clocksource.h>
 #include <linux/module.h>
 #include <linux/hardirq.h>
+#include <linux/efi.h>
 #include <linux/interrupt.h>
 #include <asm/processor.h>
 #include <asm/hypervisor.h>
@@ -23,6 +24,7 @@
 #include <asm/desc.h>
 #include <asm/idle.h>
 #include <asm/irq_regs.h>
+#include <asm/i8259.h>
 
 struct ms_hyperv_info ms_hyperv;
 EXPORT_SYMBOL_GPL(ms_hyperv);
@@ -67,6 +69,8 @@ static struct clocksource hyperv_cs = {
 
 static void __init ms_hyperv_init_platform(void)
 {
+	u64	hv_lapic_frequency;
+
 	/*
 	 * Extract the features and hints
 	 */
@@ -76,6 +80,26 @@ static void __init ms_hyperv_init_platform(void)
 	printk(KERN_INFO "HyperV: features 0x%x, hints 0x%x\n",
 	       ms_hyperv.features, ms_hyperv.hints);
 
+	if (ms_hyperv.features & HV_X64_MSR_APIC_FREQUENCY_AVAILABLE) {
+		/*
+		 * Get the APIC frequency.
+		 */
+		rdmsrl(HV_X64_MSR_APIC_FREQUENCY, hv_lapic_frequency);
+		hv_lapic_frequency = div_u64(hv_lapic_frequency, HZ);
+		lapic_timer_frequency = hv_lapic_frequency;
+		printk(KERN_INFO "HyperV: LAPIC Timer Frequency: %#x\n",
+				lapic_timer_frequency);
+
+		/*
+		 * On Hyper-V, when we are booting off an EFI firmware stack,
+		 * we do not have many legacy devices including PIC, PIT etc.
+		 */
+		if (efi_enabled(EFI_BOOT)) {
+			printk(KERN_INFO "HyperV: Using null_legacy_pic\n");
+			legacy_pic = &null_legacy_pic;
+		}
+	}
+
 	if (ms_hyperv.features & HV_X64_MSR_TIME_REF_COUNT_AVAILABLE)
 		clocksource_register_hz(&hyperv_cs, NSEC_PER_SEC/100);
 }

[patch x86/hyperv] x86, hyperv: Fix build error

[David Rientjes]

9e7827b5ea4c ("x86, hyperv: Get the local APIC timer frequency from the 
hypervisor") breaks the build with some configs because apic.h isn't 
directly included:

arch/x86/kernel/cpu/mshyperv.c: In function 'ms_hyperv_init_platform':
arch/x86/kernel/cpu/mshyperv.c:90:3: error: 'lapic_timer_frequency' undeclared (first use in this function)
arch/x86/kernel/cpu/mshyperv.c:90:3: note: each undeclared identifier is reported only once for each function it appears in

Fix it by including asm/apic.h.

Signed-off-by: David Rientjes <rientjes@google.com>
---
 arch/x86/kernel/cpu/mshyperv.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -25,6 +25,7 @@
 #include <asm/idle.h>
 #include <asm/irq_regs.h>
 #include <asm/i8259.h>
+#include <asm/apic.h>
 
 struct ms_hyperv_info ms_hyperv;
 EXPORT_SYMBOL_GPL(ms_hyperv);

RE: [patch x86/hyperv] x86, hyperv: Fix build error

[KY Srinivasan]

> -----Original Message-----
> From: David Rientjes [mailto:rientjes@google.com]
> Sent: Friday, October 11, 2013 4:08 PM
> To: Ingo Molnar; H. Peter Anvin; tglx@linutronix.de; H. Peter Anvin
> Cc: KY Srinivasan; Olaf Hering; linux-kernel@vger.kernel.org; linux-tip-
> commits@vger.kernel.org
> Subject: [patch x86/hyperv] x86, hyperv: Fix build error
> 
> 9e7827b5ea4c ("x86, hyperv: Get the local APIC timer frequency from the
> hypervisor") breaks the build with some configs because apic.h isn't
> directly included:
> 
> arch/x86/kernel/cpu/mshyperv.c: In function 'ms_hyperv_init_platform':
> arch/x86/kernel/cpu/mshyperv.c:90:3: error: 'lapic_timer_frequency' undeclared
> (first use in this function)
> arch/x86/kernel/cpu/mshyperv.c:90:3: note: each undeclared identifier is
> reported only once for each function it appears in
> 
> Fix it by including asm/apic.h.

Thank you. The issue was configuration related - local APIC was not configured. This has already been fixed.

Regards.

K. Y
> 
> Signed-off-by: David Rientjes <rientjes@google.com>
> ---
>  arch/x86/kernel/cpu/mshyperv.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
> --- a/arch/x86/kernel/cpu/mshyperv.c
> +++ b/arch/x86/kernel/cpu/mshyperv.c
> @@ -25,6 +25,7 @@
>  #include <asm/idle.h>
>  #include <asm/irq_regs.h>
>  #include <asm/i8259.h>
> +#include <asm/apic.h>
> 
>  struct ms_hyperv_info ms_hyperv;
>  EXPORT_SYMBOL_GPL(ms_hyperv);

RE: [patch x86/hyperv] x86, hyperv: Fix build error

[David Rientjes]

On Fri, 11 Oct 2013, KY Srinivasan wrote:

> > From: David Rientjes [mailto:rientjes@google.com]
> > Sent: Friday, October 11, 2013 4:08 PM
> > To: Ingo Molnar; H. Peter Anvin; tglx@linutronix.de; H. Peter Anvin
> > Cc: KY Srinivasan; Olaf Hering; linux-kernel@vger.kernel.org; linux-tip-
> > commits@vger.kernel.org
> > Subject: [patch x86/hyperv] x86, hyperv: Fix build error
> > 
> > 9e7827b5ea4c ("x86, hyperv: Get the local APIC timer frequency from the
> > hypervisor") breaks the build with some configs because apic.h isn't
> > directly included:
> > 
> > arch/x86/kernel/cpu/mshyperv.c: In function 'ms_hyperv_init_platform':
> > arch/x86/kernel/cpu/mshyperv.c:90:3: error: 'lapic_timer_frequency' undeclared
> > (first use in this function)
> > arch/x86/kernel/cpu/mshyperv.c:90:3: note: each undeclared identifier is
> > reported only once for each function it appears in
> > 
> > Fix it by including asm/apic.h.
> 
> Thank you. The issue was configuration related - local APIC was not configured. This has already been fixed.
> 

Yeah, it's config related as stated in the changelog.  If you're referring 
to 90ab9d551093 ("x86, hyperv: Correctly guard the local APIC calibration 
code ")as "fixing" it, it does not.  (I'm left to wonder what you mean by 
it being fixed since you didn't elaborate.)  You can trigger this build 
breakage even with CONFIG_X86_LOCAL_APIC=y.

Let me be explicit: this file includes desc.h, which includes linux/smp.h, 
which includes asm/smp.h iff CONFIG_SMP is enabled.  That's what you're 
relying upon to get asm/apic.h when CONFIG_X86_LOCAL_APIC is enabled.  It 
will break when CONFIG_SMP is disabled.

So you need to include asm/apic.h directly for such a configuration.

RE: [patch x86/hyperv] x86, hyperv: Fix build error

[KY Srinivasan]

> -----Original Message-----
> From: David Rientjes [mailto:rientjes@google.com]
> Sent: Friday, October 11, 2013 4:29 PM
> To: KY Srinivasan
> Cc: Ingo Molnar; H. Peter Anvin; tglx@linutronix.de; H. Peter Anvin; Olaf Hering;
> linux-kernel@vger.kernel.org; linux-tip-commits@vger.kernel.org
> Subject: RE: [patch x86/hyperv] x86, hyperv: Fix build error
> 
> On Fri, 11 Oct 2013, KY Srinivasan wrote:
> 
> > > From: David Rientjes [mailto:rientjes@google.com]
> > > Sent: Friday, October 11, 2013 4:08 PM
> > > To: Ingo Molnar; H. Peter Anvin; tglx@linutronix.de; H. Peter Anvin
> > > Cc: KY Srinivasan; Olaf Hering; linux-kernel@vger.kernel.org; linux-tip-
> > > commits@vger.kernel.org
> > > Subject: [patch x86/hyperv] x86, hyperv: Fix build error
> > >
> > > 9e7827b5ea4c ("x86, hyperv: Get the local APIC timer frequency from the
> > > hypervisor") breaks the build with some configs because apic.h isn't
> > > directly included:
> > >
> > > arch/x86/kernel/cpu/mshyperv.c: In function 'ms_hyperv_init_platform':
> > > arch/x86/kernel/cpu/mshyperv.c:90:3: error: 'lapic_timer_frequency'
> undeclared
> > > (first use in this function)
> > > arch/x86/kernel/cpu/mshyperv.c:90:3: note: each undeclared identifier is
> > > reported only once for each function it appears in
> > >
> > > Fix it by including asm/apic.h.
> >
> > Thank you. The issue was configuration related - local APIC was not configured.
> This has already been fixed.
> >
> 
> Yeah, it's config related as stated in the changelog.  If you're referring
> to 90ab9d551093 ("x86, hyperv: Correctly guard the local APIC calibration
> code ")as "fixing" it, it does not.  (I'm left to wonder what you mean by
> it being fixed since you didn't elaborate.)  You can trigger this build
> breakage even with CONFIG_X86_LOCAL_APIC=y.
> 
> Let me be explicit: this file includes desc.h, which includes linux/smp.h,
> which includes asm/smp.h iff CONFIG_SMP is enabled.  That's what you're
> relying upon to get asm/apic.h when CONFIG_X86_LOCAL_APIC is enabled.  It
> will break when CONFIG_SMP is disabled.
> 
> So you need to include asm/apic.h directly for such a configuration.

Thank you for the details.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>

Regards,

K. Y

[patch x86/hyperv resend] x86, hyperv: Fix build error

[David Rientjes]

9e7827b5ea4c ("x86, hyperv: Get the local APIC timer frequency from the 
hypervisor") breaks the build when CONFIG_SMP is disabled because apic.h 
isn't directly included:

arch/x86/kernel/cpu/mshyperv.c: In function 'ms_hyperv_init_platform':
arch/x86/kernel/cpu/mshyperv.c:90:3: error: 'lapic_timer_frequency' undeclared (first use in this function)
arch/x86/kernel/cpu/mshyperv.c:90:3: note: each undeclared identifier is reported only once for each function it appears in

This happens because mshyperv.c includes linux/desc.h, which includes 
linux/smp.h, which includes asm/smp.h iff CONFIG_SMP is enabled, and 
asm/smp.h is what includes asm/apic.h for CONFIG_X86_LOCAL_APIC.

Fix it by directly including asm/apic.h.

Acked-by: "K. Y. Srinivasan" <kys@microsoft.com>
Signed-off-by: David Rientjes <rientjes@google.com>
---
 arch/x86/kernel/cpu/mshyperv.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -25,6 +25,7 @@
 #include <asm/idle.h>
 #include <asm/irq_regs.h>
 #include <asm/i8259.h>
+#include <asm/apic.h>
 
 struct ms_hyperv_info ms_hyperv;
 EXPORT_SYMBOL_GPL(ms_hyperv);

[tip:x86/hyperv] x86, hyperv: Fix build error due to missing <asm /apic.h> include

[tip-bot for David Rientjes]

Commit-ID:  d68ce0177c1e51fb332369e0c99852a6d05668af
Gitweb:     http://git.kernel.org/tip/d68ce0177c1e51fb332369e0c99852a6d05668af
Author:     David Rientjes <rientjes@google.com>
AuthorDate: Fri, 11 Oct 2013 16:07:31 -0700
Committer:  H. Peter Anvin <hpa@linux.intel.com>
CommitDate: Wed, 30 Oct 2013 15:37:47 -0700

x86, hyperv: Fix build error due to missing <asm/apic.h> include

9e7827b5ea4c ("x86, hyperv: Get the local APIC timer frequency from the
hypervisor") breaks the build with some configs because apic.h isn't
directly included:

arch/x86/kernel/cpu/mshyperv.c: In function 'ms_hyperv_init_platform':
arch/x86/kernel/cpu/mshyperv.c:90:3: error: 'lapic_timer_frequency' undeclared (first use in this function)
arch/x86/kernel/cpu/mshyperv.c:90:3: note: each undeclared identifier is reported only once for each function it appears in

Fix it by including asm/apic.h.

Signed-off-by: David Rientjes <rientjes@google.com>
Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1310111604160.31170@chino.kir.corp.google.com
Acked-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
---
 arch/x86/kernel/cpu/mshyperv.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 628ff50..9f6e9f8 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -25,6 +25,7 @@
 #include <asm/idle.h>
 #include <asm/irq_regs.h>
 #include <asm/i8259.h>
+#include <asm/apic.h>
 
 struct ms_hyperv_info ms_hyperv;
 EXPORT_SYMBOL_GPL(ms_hyperv);