Gerd Hoffmann wrote:
> This patch updates the xen guest to use the pvclock structs
> and helper functions.
>
> Signed-off-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
> ---
> arch/x86/xen/Kconfig | 1 +
> arch/x86/xen/time.c | 130 ++++---------------------------------------
> include/xen/interface/xen.h | 5 +-
> 3 files changed, 14 insertions(+), 122 deletions(-)
>
> diff --git a/arch/x86/xen/Kconfig b/arch/x86/xen/Kconfig
> index 2e641be..3a4f16a 100644
> --- a/arch/x86/xen/Kconfig
> +++ b/arch/x86/xen/Kconfig
> @@ -5,6 +5,7 @@
> config XEN
> bool "Xen guest support"
> select PARAVIRT
> + select PARAVIRT_CLOCK
> depends on X86_32
> depends on X86_CMPXCHG && X86_TSC && !(X86_VISWS || X86_VOYAGER)
> help
> diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
> index c39e1a5..bf31fb5 100644
> --- a/arch/x86/xen/time.c
> +++ b/arch/x86/xen/time.c
> @@ -13,6 +13,7 @@
> #include <linux/clockchips.h>
> #include <linux/kernel_stat.h>
>
> +#include <asm/pvclock.h>
> #include <asm/xen/hypervisor.h>
> #include <asm/xen/hypercall.h>
>
> @@ -30,17 +31,6 @@
>
> static cycle_t xen_clocksource_read(void);
>
> -/* These are perodically updated in shared_info, and then copied here. */
> -struct shadow_time_info {
> - u64 tsc_timestamp; /* TSC at last update of time vals. */
> - u64 system_timestamp; /* Time, in nanosecs, since boot. */
> - u32 tsc_to_nsec_mul;
> - int tsc_shift;
> - u32 version;
> -};
> -
> -static DEFINE_PER_CPU(struct shadow_time_info, shadow_time);
> -
> /* runstate info updated by Xen */
> static DEFINE_PER_CPU(struct vcpu_runstate_info, runstate);
>
> @@ -230,121 +220,26 @@ unsigned long xen_cpu_khz(void)
> return xen_khz;
> }
>
> -/*
> - * Reads a consistent set of time-base values from Xen, into a shadow data
> - * area.
> - */
> -static unsigned get_time_values_from_xen(void)
> -{
> - struct vcpu_time_info *src;
> - struct shadow_time_info *dst;
> -
> - /* src is shared memory with the hypervisor, so we need to
> - make sure we get a consistent snapshot, even in the face of
> - being preempted. */
> - src = &__get_cpu_var(xen_vcpu)->time;
> - dst = &__get_cpu_var(shadow_time);
> -
> - do {
> - dst->version = src->version;
> - rmb(); /* fetch version before data */
> - dst->tsc_timestamp = src->tsc_timestamp;
> - dst->system_timestamp = src->system_time;
> - dst->tsc_to_nsec_mul = src->tsc_to_system_mul;
> - dst->tsc_shift = src->tsc_shift;
> - rmb(); /* test version after fetching data */
> - } while ((src->version & 1) | (dst->version ^ src->version));
> -
> - return dst->version;
> -}
> -
> -/*
> - * Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction,
> - * yielding a 64-bit result.
> - */
> -static inline u64 scale_delta(u64 delta, u32 mul_frac, int shift)
> -{
> - u64 product;
> -#ifdef __i386__
> - u32 tmp1, tmp2;
> -#endif
> -
> - if (shift < 0)
> - delta >>= -shift;
> - else
> - delta <<= shift;
> -
> -#ifdef __i386__
> - __asm__ (
> - "mul %5 ; "
> - "mov %4,%%eax ; "
> - "mov %%edx,%4 ; "
> - "mul %5 ; "
> - "xor %5,%5 ; "
> - "add %4,%%eax ; "
> - "adc %5,%%edx ; "
> - : "=A" (product), "=r" (tmp1), "=r" (tmp2)
> - : "a" ((u32)delta), "1" ((u32)(delta >> 32)), "2" (mul_frac) );
> -#elif __x86_64__
> - __asm__ (
> - "mul %%rdx ; shrd $32,%%rdx,%%rax"
> - : "=a" (product) : "0" (delta), "d" ((u64)mul_frac) );
> -#else
> -#error implement me!
> -#endif
> -
> - return product;
> -}
> -
> -static u64 get_nsec_offset(struct shadow_time_info *shadow)
> -{
> - u64 now, delta;
> - now = native_read_tsc();
> - delta = now - shadow->tsc_timestamp;
> - return scale_delta(delta, shadow->tsc_to_nsec_mul, shadow->tsc_shift);
> -}
> -
> static cycle_t xen_clocksource_read(void)
> {
> - struct shadow_time_info *shadow = &get_cpu_var(shadow_time);
> + struct vcpu_time_info *src;
> cycle_t ret;
> - unsigned version;
> -
> - do {
> - version = get_time_values_from_xen();
> - barrier();
> - ret = shadow->system_timestamp + get_nsec_offset(shadow);
> - barrier();
> - } while (version != __get_cpu_var(xen_vcpu)->time.version);
> -
> - put_cpu_var(shadow_time);
>
> + src = &get_cpu_var(xen_vcpu)->time;
> + ret = pvclock_clocksource_read((void*)src);
> + put_cpu_var(xen_vcpu);
> return ret;
> }
>
> static void xen_read_wallclock(struct timespec *ts)
> {
> - const struct shared_info *s = HYPERVISOR_shared_info;
> - u32 version;
> - u64 delta;
> - struct timespec now;
> -
> - /* get wallclock at system boot */
> - do {
> - version = s->wc_version;
> - rmb(); /* fetch version before time */
> - now.tv_sec = s->wc_sec;
> - now.tv_nsec = s->wc_nsec;
> - rmb(); /* fetch time before checking version */
> - } while ((s->wc_version & 1) | (version ^ s->wc_version));
> + struct shared_info *s = HYPERVISOR_shared_info;
> + struct pvclock_wall_clock *wall_clock = &(s->wc);
> + struct vcpu_time_info *vcpu_time;
>
> - delta = xen_clocksource_read(); /* time since system boot */
> - delta += now.tv_sec * (u64)NSEC_PER_SEC + now.tv_nsec;
> -
> - now.tv_nsec = do_div(delta, NSEC_PER_SEC);
> - now.tv_sec = delta;
> -
> - set_normalized_timespec(ts, now.tv_sec, now.tv_nsec);
> + vcpu_time = &get_cpu_var(xen_vcpu)->time;
> + pvclock_read_wallclock(wall_clock, (void*)vcpu_time, ts);
>
Why this cast here? Because the corresponding struct in vcpu_info
hasn't been updated to match?
J
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