Re: [PATCH v6 1/4] x86/pvclock: add setter for pvclock_pvti_cpu0_va

From: Joao Martins
Date: Tue Oct 17 2017 - 11:34:53 EST


On 10/03/2017 12:55 PM, Joao Martins 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 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@xxxxxxxxxx>
> Acked-by: Andy Lutomirski <luto@xxxxxxxxxx>

Ping?

While the rest of series has been acked, I think that this patch (per
maintainers file) still misses x86 and (or?) kvm ack/review.

Joao

> ---
> 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);
>