linux-kernel - Re: [PATCH v6 1/4] x86/pvclock: add setter for pvclock_pvti_cpu0

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Date:   Tue, 17 Oct 2017 16:34:23 +0100
From:   Joao Martins <joao.m.martins@...cle.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krcmar <rkrcmar@...hat.com>,
        Andy Lutomirski <luto@...capital.net>,
        xen-devel <xen-devel@...ts.xenproject.org>,
        Juergen Gross <JGross@...e.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>
Subject: Re: [PATCH v6 1/4] x86/pvclock: add setter for pvclock_pvti_cpu0_va

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@...cle.com>
> Acked-by: Andy Lutomirski <luto@...nel.org>

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);
>