diff mbox

[v1,1/3] x86/pvclock: add setter for pvclock_pvti_cpu0_va

Message ID 1485365586-21653-2-git-send-email-joao.m.martins@oracle.com (mailing list archive)
State New, archived
Headers show

Commit Message

Joao Martins Jan. 25, 2017, 5:33 p.m. UTC
Right now there is only a pvclock_pvti_cpu0_va() which is defined
on kvmclock since:

commit dac16fba6fc5
("x86/vdso: Get pvclock data from the vvar VMA instead of the fixmap")

The only user of this interface was kvm. This commit moves
pvclock_pvti_cpu0_va to pvclock which is a more generic place to have it
and adds the correspondent setter routine for it. This allows other
pvclock-based clocksources to use it, such as Xen.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
---
Changes since RFC:
 (Comments from Andy Lutomirski)
 * Add WARN_ON(vclock_was_used(VCLOCK_PVCLOCK)) to
 pvclock_set_pvti_cpu0_va
---
 arch/x86/include/asm/pvclock.h | 22 +++++++++++++---------
 arch/x86/kernel/kvmclock.c     |  6 +-----
 arch/x86/kernel/pvclock.c      | 13 +++++++++++++
 3 files changed, 27 insertions(+), 14 deletions(-)

Comments

Andy Lutomirski Jan. 26, 2017, 5:25 p.m. UTC | #1
On Wed, Jan 25, 2017 at 9:33 AM, Joao Martins <joao.m.martins@oracle.com> wrote:
> Right now there is only a pvclock_pvti_cpu0_va() which is defined
> on kvmclock since:
>
> commit dac16fba6fc5
> ("x86/vdso: Get pvclock data from the vvar VMA instead of the fixmap")
>
> The only user of this interface was kvm. This commit moves
> pvclock_pvti_cpu0_va to pvclock which is a more generic place to have it
> and adds the correspondent setter routine for it. This allows other
> pvclock-based clocksources to use it, such as Xen.

With a minor nit:

Acked-by: Andy Lutomirski <luto@kernel.org>

> +#else
> +static inline void pvclock_set_pvti_cpu0_va(struct pvclock_vsyscall_time_info *pvti)
> +{
> +}

How about just not providing pvclock_set_pvti_cpu0_va() in this case?
It'll save three lines of code, and, more importantly, it will force
us to notice if we screw up the Kconfig stuff.
Joao Martins Jan. 26, 2017, 7:58 p.m. UTC | #2
On 01/26/2017 05:25 PM, Andy Lutomirski wrote:
> On Wed, Jan 25, 2017 at 9:33 AM, Joao Martins <joao.m.martins@oracle.com> wrote:
>> Right now there is only a pvclock_pvti_cpu0_va() which is defined
>> on kvmclock since:
>>
>> commit dac16fba6fc5
>> ("x86/vdso: Get pvclock data from the vvar VMA instead of the fixmap")
>>
>> The only user of this interface was kvm. This commit moves
>> pvclock_pvti_cpu0_va to pvclock which is a more generic place to have it
>> and adds the correspondent setter routine for it. This allows other
>> pvclock-based clocksources to use it, such as Xen.
> 
> With a minor nit:
> 
> Acked-by: Andy Lutomirski <luto@kernel.org>
> 
>> +#else
>> +static inline void pvclock_set_pvti_cpu0_va(struct pvclock_vsyscall_time_info *pvti)
>> +{
>> +}
> 
> How about just not providing pvclock_set_pvti_cpu0_va() in this case?
> It'll save three lines of code, and, more importantly, it will force
> us to notice if we screw up the Kconfig stuff.
Sounds good, will remove this then. Thanks!

Joao
diff mbox

Patch

diff --git a/arch/x86/include/asm/pvclock.h b/arch/x86/include/asm/pvclock.h
index 448cfe1..58399e1 100644
--- a/arch/x86/include/asm/pvclock.h
+++ b/arch/x86/include/asm/pvclock.h
@@ -4,15 +4,6 @@ 
 #include <linux/clocksource.h>
 #include <asm/pvclock-abi.h>
 
-#ifdef CONFIG_KVM_GUEST
-extern struct pvclock_vsyscall_time_info *pvclock_pvti_cpu0_va(void);
-#else
-static inline struct pvclock_vsyscall_time_info *pvclock_pvti_cpu0_va(void)
-{
-	return NULL;
-}
-#endif
-
 /* some helper functions for xen and kvm pv clock sources */
 u64 pvclock_clocksource_read(struct pvclock_vcpu_time_info *src);
 u8 pvclock_read_flags(struct pvclock_vcpu_time_info *src);
@@ -101,4 +92,17 @@  struct pvclock_vsyscall_time_info {
 
 #define PVTI_SIZE sizeof(struct pvclock_vsyscall_time_info)
 
+#ifdef CONFIG_PARAVIRT_CLOCK
+void pvclock_set_pvti_cpu0_va(struct pvclock_vsyscall_time_info *pvti);
+struct pvclock_vsyscall_time_info *pvclock_pvti_cpu0_va(void);
+#else
+static inline void pvclock_set_pvti_cpu0_va(struct pvclock_vsyscall_time_info *pvti)
+{
+}
+static inline struct pvclock_vsyscall_time_info *pvclock_pvti_cpu0_va(void)
+{
+	return NULL;
+}
+#endif
+
 #endif /* _ASM_X86_PVCLOCK_H */
diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
index 2a5cafd..9dfbb79 100644
--- a/arch/x86/kernel/kvmclock.c
+++ b/arch/x86/kernel/kvmclock.c
@@ -45,11 +45,6 @@  early_param("no-kvmclock", parse_no_kvmclock);
 static struct pvclock_vsyscall_time_info *hv_clock;
 static struct pvclock_wall_clock wall_clock;
 
-struct pvclock_vsyscall_time_info *pvclock_pvti_cpu0_va(void)
-{
-	return hv_clock;
-}
-
 /*
  * The wallclock is the time of day when we booted. Since then, some time may
  * have elapsed since the hypervisor wrote the data. So we try to account for
@@ -330,6 +325,7 @@  int __init kvm_setup_vsyscall_timeinfo(void)
 		return 1;
 	}
 
+	pvclock_set_pvti_cpu0_va(hv_clock);
 	put_cpu();
 
 	kvm_clock.archdata.vclock_mode = VCLOCK_PVCLOCK;
diff --git a/arch/x86/kernel/pvclock.c b/arch/x86/kernel/pvclock.c
index 9e93fe5..b281060 100644
--- a/arch/x86/kernel/pvclock.c
+++ b/arch/x86/kernel/pvclock.c
@@ -23,8 +23,10 @@ 
 #include <linux/bootmem.h>
 #include <asm/fixmap.h>
 #include <asm/pvclock.h>
+#include <asm/vgtod.h>
 
 static u8 valid_flags __read_mostly = 0;
+static struct pvclock_vsyscall_time_info *pvti_cpu0_va __read_mostly = NULL;
 
 void pvclock_set_flags(u8 flags)
 {
@@ -142,3 +144,14 @@  void pvclock_read_wallclock(struct pvclock_wall_clock *wall_clock,
 
 	set_normalized_timespec(ts, now.tv_sec, now.tv_nsec);
 }
+
+void pvclock_set_pvti_cpu0_va(struct pvclock_vsyscall_time_info *pvti)
+{
+	WARN_ON(vclock_was_used(VCLOCK_PVCLOCK));
+	pvti_cpu0_va = pvti;
+}
+
+struct pvclock_vsyscall_time_info *pvclock_pvti_cpu0_va(void)
+{
+	return pvti_cpu0_va;
+}