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Subject[PATCH v6 1/4] x86/pvclock: add setter for pvclock_pvti_cpu0_va
Date
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 so far is kvm. This commit adds a
setter function for the pvti page and moves pvclock_pvti_cpu0_va
to pvclock, which is a more generic place to have it; and would
allow other PV clocksources to use it, such as Xen.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Acked-by: Andy Lutomirski <luto@kernel.org>
---
Changes since v1:
* Rebased: the only conflict was that I had move the export
pvclock_pvti_cpu0_va() symbol as it is used by kvm PTP driver.
* Do not initialize pvti_cpu0_va to NULL (checkpatch error)
( Comments from Andy Lutomirski )
* Removed asm/pvclock.h 'pvclock_set_pvti_cpu0_va' definition
for non !PARAVIRT_CLOCK to better track screwed Kconfig stuff.
* Add his Acked-by (provided the previous adjustment was made)

Changes since RFC:
(Comments from Andy Lutomirski)
* Add __init to pvclock_set_pvti_cpu0_va
* Add WARN_ON(vclock_was_used(VCLOCK_PVCLOCK)) to
pvclock_set_pvti_cpu0_va
---
arch/x86/include/asm/pvclock.h | 19 ++++++++++---------
arch/x86/kernel/kvmclock.c | 7 +------
arch/x86/kernel/pvclock.c | 14 ++++++++++++++
3 files changed, 25 insertions(+), 15 deletions(-)

diff --git a/arch/x86/include/asm/pvclock.h b/arch/x86/include/asm/pvclock.h
index 448cfe1b48cf..6f228f90cdd7 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 +92,14 @@ 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 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 d88967659098..538738047ff5 100644
--- a/arch/x86/kernel/kvmclock.c
+++ b/arch/x86/kernel/kvmclock.c
@@ -47,12 +47,6 @@ 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;
-}
-EXPORT_SYMBOL_GPL(pvclock_pvti_cpu0_va);
-
/*
* 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
@@ -334,6 +328,7 @@ 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 5c3f6d6a5078..cb7d6d9c9c2d 100644
--- a/arch/x86/kernel/pvclock.c
+++ b/arch/x86/kernel/pvclock.c
@@ -25,8 +25,10 @@

#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;

void pvclock_set_flags(u8 flags)
{
@@ -144,3 +146,15 @@ 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;
+}
+EXPORT_SYMBOL_GPL(pvclock_pvti_cpu0_va);
--
2.11.0
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