From 3565184ed0c1ea46bea5b792da5f72a83c43e49b Mon Sep 17 00:00:00 2001 From: David Vrabel Date: Mon, 13 May 2013 18:56:06 +0100 Subject: [PATCH] x86: Increase precision of x86_platform.get/set_wallclock() All the virtualized platforms (KVM, lguest and Xen) have persistent wallclocks that have more than one second of precision. read_persistent_wallclock() and update_persistent_wallclock() allow for nanosecond precision but their implementation on x86 with x86_platform.get/set_wallclock() only allows for one second precision. This means guests may see a wallclock time that is off by up to 1 second. Make set_wallclock() and get_wallclock() take a struct timespec parameter (which allows for nanosecond precision) so KVM and Xen guests may start with a more accurate wallclock time and a Xen dom0 can maintain a more accurate wallclock for guests. Signed-off-by: David Vrabel Signed-off-by: John Stultz --- arch/x86/include/asm/mc146818rtc.h | 4 ++-- arch/x86/include/asm/x86_init.h | 6 ++++-- arch/x86/kernel/kvmclock.c | 9 +++------ arch/x86/kernel/rtc.c | 17 +++++++---------- arch/x86/lguest/boot.c | 4 ++-- arch/x86/platform/efi/efi.c | 10 ++++++---- arch/x86/xen/time.c | 19 ++++++------------- include/linux/efi.h | 4 ++-- 8 files changed, 32 insertions(+), 41 deletions(-) diff --git a/arch/x86/include/asm/mc146818rtc.h b/arch/x86/include/asm/mc146818rtc.h index d354fb7..a55c7ef 100644 --- a/arch/x86/include/asm/mc146818rtc.h +++ b/arch/x86/include/asm/mc146818rtc.h @@ -95,8 +95,8 @@ static inline unsigned char current_lock_cmos_reg(void) unsigned char rtc_cmos_read(unsigned char addr); void rtc_cmos_write(unsigned char val, unsigned char addr); -extern int mach_set_rtc_mmss(unsigned long nowtime); -extern unsigned long mach_get_cmos_time(void); +extern int mach_set_rtc_mmss(const struct timespec *now); +extern void mach_get_cmos_time(struct timespec *now); #define RTC_IRQ 8 diff --git a/arch/x86/include/asm/x86_init.h b/arch/x86/include/asm/x86_init.h index d8d9922..828a156 100644 --- a/arch/x86/include/asm/x86_init.h +++ b/arch/x86/include/asm/x86_init.h @@ -142,6 +142,8 @@ struct x86_cpuinit_ops { void (*fixup_cpu_id)(struct cpuinfo_x86 *c, int node); }; +struct timespec; + /** * struct x86_platform_ops - platform specific runtime functions * @calibrate_tsc: calibrate TSC @@ -156,8 +158,8 @@ struct x86_cpuinit_ops { */ struct x86_platform_ops { unsigned long (*calibrate_tsc)(void); - unsigned long (*get_wallclock)(void); - int (*set_wallclock)(unsigned long nowtime); + void (*get_wallclock)(struct timespec *ts); + int (*set_wallclock)(const struct timespec *ts); void (*iommu_shutdown)(void); bool (*is_untracked_pat_range)(u64 start, u64 end); void (*nmi_init)(void); diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c index d2c3812..0db81ab 100644 --- a/arch/x86/kernel/kvmclock.c +++ b/arch/x86/kernel/kvmclock.c @@ -48,10 +48,9 @@ static struct pvclock_wall_clock wall_clock; * have elapsed since the hypervisor wrote the data. So we try to account for * that with system time */ -static unsigned long kvm_get_wallclock(void) +static void kvm_get_wallclock(struct timespec *now) { struct pvclock_vcpu_time_info *vcpu_time; - struct timespec ts; int low, high; int cpu; @@ -64,14 +63,12 @@ static unsigned long kvm_get_wallclock(void) cpu = smp_processor_id(); vcpu_time = &hv_clock[cpu].pvti; - pvclock_read_wallclock(&wall_clock, vcpu_time, &ts); + pvclock_read_wallclock(&wall_clock, vcpu_time, now); preempt_enable(); - - return ts.tv_sec; } -static int kvm_set_wallclock(unsigned long now) +static int kvm_set_wallclock(const struct timespec *now) { return -1; } diff --git a/arch/x86/kernel/rtc.c b/arch/x86/kernel/rtc.c index 198eb20..0aa2939 100644 --- a/arch/x86/kernel/rtc.c +++ b/arch/x86/kernel/rtc.c @@ -38,8 +38,9 @@ EXPORT_SYMBOL(rtc_lock); * jump to the next second precisely 500 ms later. Check the Motorola * MC146818A or Dallas DS12887 data sheet for details. */ -int mach_set_rtc_mmss(unsigned long nowtime) +int mach_set_rtc_mmss(const struct timespec *now) { + unsigned long nowtime = now->tv_sec; struct rtc_time tm; int retval = 0; @@ -58,7 +59,7 @@ int mach_set_rtc_mmss(unsigned long nowtime) return retval; } -unsigned long mach_get_cmos_time(void) +void mach_get_cmos_time(struct timespec *now) { unsigned int status, year, mon, day, hour, min, sec, century = 0; unsigned long flags; @@ -107,7 +108,8 @@ unsigned long mach_get_cmos_time(void) } else year += CMOS_YEARS_OFFS; - return mktime(year, mon, day, hour, min, sec); + now->tv_sec = mktime(year, mon, day, hour, min, sec); + now->tv_nsec = 0; } /* Routines for accessing the CMOS RAM/RTC. */ @@ -135,18 +137,13 @@ EXPORT_SYMBOL(rtc_cmos_write); int update_persistent_clock(struct timespec now) { - return x86_platform.set_wallclock(now.tv_sec); + return x86_platform.set_wallclock(&now); } /* not static: needed by APM */ void read_persistent_clock(struct timespec *ts) { - unsigned long retval; - - retval = x86_platform.get_wallclock(); - - ts->tv_sec = retval; - ts->tv_nsec = 0; + x86_platform.get_wallclock(ts); } diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c index 7114c63..8424d5a 100644 --- a/arch/x86/lguest/boot.c +++ b/arch/x86/lguest/boot.c @@ -882,9 +882,9 @@ int lguest_setup_irq(unsigned int irq) * It would be far better for everyone if the Guest had its own clock, but * until then the Host gives us the time on every interrupt. */ -static unsigned long lguest_get_wallclock(void) +static void lguest_get_wallclock(struct timespec *now) { - return lguest_data.time.tv_sec; + *now = lguest_data.time; } /* diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c index 55856b2..dd3b825 100644 --- a/arch/x86/platform/efi/efi.c +++ b/arch/x86/platform/efi/efi.c @@ -352,8 +352,9 @@ static efi_status_t __init phys_efi_get_time(efi_time_t *tm, return status; } -int efi_set_rtc_mmss(unsigned long nowtime) +int efi_set_rtc_mmss(const struct timespec *now) { + unsigned long nowtime = now->tv_sec; efi_status_t status; efi_time_t eft; efi_time_cap_t cap; @@ -388,7 +389,7 @@ int efi_set_rtc_mmss(unsigned long nowtime) return 0; } -unsigned long efi_get_time(void) +void efi_get_time(struct timespec *now) { efi_status_t status; efi_time_t eft; @@ -398,8 +399,9 @@ unsigned long efi_get_time(void) if (status != EFI_SUCCESS) pr_err("Oops: efitime: can't read time!\n"); - return mktime(eft.year, eft.month, eft.day, eft.hour, - eft.minute, eft.second); + now->tv_sec = mktime(eft.year, eft.month, eft.day, eft.hour, + eft.minute, eft.second); + now->tv_nsec = 0; } /* diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c index 3d88bfd..a1947ac 100644 --- a/arch/x86/xen/time.c +++ b/arch/x86/xen/time.c @@ -191,32 +191,25 @@ static void xen_read_wallclock(struct timespec *ts) put_cpu_var(xen_vcpu); } -static unsigned long xen_get_wallclock(void) +static void xen_get_wallclock(struct timespec *now) { - struct timespec ts; - - xen_read_wallclock(&ts); - return ts.tv_sec; + xen_read_wallclock(now); } -static int xen_set_wallclock(unsigned long now) +static int xen_set_wallclock(const struct timespec *now) { struct xen_platform_op op; - int rc; /* do nothing for domU */ if (!xen_initial_domain()) return -1; op.cmd = XENPF_settime; - op.u.settime.secs = now; - op.u.settime.nsecs = 0; + op.u.settime.secs = now->tv_sec; + op.u.settime.nsecs = now->tv_nsec; op.u.settime.system_time = xen_clocksource_read(); - rc = HYPERVISOR_dom0_op(&op); - WARN(rc != 0, "XENPF_settime failed: now=%ld\n", now); - - return rc; + return HYPERVISOR_dom0_op(&op); } static struct clocksource xen_clocksource __read_mostly = { diff --git a/include/linux/efi.h b/include/linux/efi.h index 2bc0ad7..0068bba 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -594,8 +594,8 @@ extern u64 efi_mem_attribute (unsigned long phys_addr, unsigned long size); extern int __init efi_uart_console_only (void); extern void efi_initialize_iomem_resources(struct resource *code_resource, struct resource *data_resource, struct resource *bss_resource); -extern unsigned long efi_get_time(void); -extern int efi_set_rtc_mmss(unsigned long nowtime); +extern void efi_get_time(struct timespec *now); +extern int efi_set_rtc_mmss(const struct timespec *now); extern void efi_reserve_boot_services(void); extern struct efi_memory_map memmap; -- 2.7.4