diff options
author | bryanv <bryanv@FreeBSD.org> | 2015-02-04 08:26:43 +0000 |
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committer | bryanv <bryanv@FreeBSD.org> | 2015-02-04 08:26:43 +0000 |
commit | 25ce9181cfd88fce73c121eaab1a8e5237d61dda (patch) | |
tree | 98f4954cbd87507fe4414ae222b3a687719fd649 /sys/x86 | |
parent | c15561b95df1328a7256de3d0bd80389501ce03f (diff) | |
download | FreeBSD-src-25ce9181cfd88fce73c121eaab1a8e5237d61dda.zip FreeBSD-src-25ce9181cfd88fce73c121eaab1a8e5237d61dda.tar.gz |
Generalized parts of the XEN timer code into a generic pvclock
KVM clock shares the same data structures between the guest and the host
as Xen so it makes sense to just have a single copy of this code.
Differential Revision: https://reviews.freebsd.org/D1429
Reviewed by: royger (eariler version)
MFC after: 1 month
Diffstat (limited to 'sys/x86')
-rw-r--r-- | sys/x86/include/pvclock.h | 58 | ||||
-rw-r--r-- | sys/x86/x86/pvclock.c | 188 |
2 files changed, 246 insertions, 0 deletions
diff --git a/sys/x86/include/pvclock.h b/sys/x86/include/pvclock.h new file mode 100644 index 0000000..88a596f --- /dev/null +++ b/sys/x86/include/pvclock.h @@ -0,0 +1,58 @@ +/*- + * Copyright (c) 2014, Bryan Venteicher <bryanv@FreeBSD.org> + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * $FreeBSD$ + */ + +#ifndef X86_PVCLOCK +#define X86_PVCLOCK + +struct pvclock_vcpu_time_info { + uint32_t version; + uint32_t pad0; + uint64_t tsc_timestamp; + uint64_t system_time; + uint32_t tsc_to_system_mul; + int8_t tsc_shift; + uint8_t flags; + uint8_t pad[2]; +}; + +#define PVCLOCK_FLAG_TSC_STABLE 0x01 +#define PVCLOCK_FLAG_GUEST_PASUED 0x02 + +struct pvclock_wall_clock { + uint32_t version; + uint32_t sec; + uint32_t nsec; +}; + +void pvclock_resume(void); +uint64_t pvclock_get_last_cycles(void); +uint64_t pvclock_get_timecount(struct pvclock_vcpu_time_info *ti); +void pvclock_get_wallclock(struct pvclock_wall_clock *wc, + struct timespec *ts); + +#endif diff --git a/sys/x86/x86/pvclock.c b/sys/x86/x86/pvclock.c new file mode 100644 index 0000000..ebc37a4 --- /dev/null +++ b/sys/x86/x86/pvclock.c @@ -0,0 +1,188 @@ +/*- + * Copyright (c) 2009 Adrian Chadd + * Copyright (c) 2012 Spectra Logic Corporation + * Copyright (c) 2014 Bryan Venteicher + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#include <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include <sys/param.h> +#include <sys/systm.h> +#include <sys/proc.h> + +#include <machine/cpufunc.h> +#include <machine/cpu.h> +#include <machine/atomic.h> +#include <machine/pvclock.h> + +/* + * Last time; this guarantees a monotonically increasing clock for when + * a stable TSC is not provided. + */ +static volatile uint64_t pvclock_last_cycles; + +void +pvclock_resume(void) +{ + + atomic_store_rel_64(&pvclock_last_cycles, 0); +} + +uint64_t +pvclock_get_last_cycles(void) +{ + + return (atomic_load_acq_64(&pvclock_last_cycles)); +} + +/* + * Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction, + * yielding a 64-bit result. + */ +static inline uint64_t +pvclock_scale_delta(uint64_t delta, uint32_t mul_frac, int shift) +{ + uint64_t product; + + if (shift < 0) + delta >>= -shift; + else + delta <<= shift; + +#if defined(__i386__) + { + uint32_t tmp1, tmp2; + + /** + * For i386, the formula looks like: + * + * lower = (mul_frac * (delta & UINT_MAX)) >> 32 + * upper = mul_frac * (delta >> 32) + * product = lower + upper + */ + __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" ((uint32_t)delta), "1" ((uint32_t)(delta >> 32)), + "2" (mul_frac) ); + } +#elif defined(__amd64__) + { + unsigned long tmp; + + __asm__ ( + "mulq %[mul_frac] ; shrd $32, %[hi], %[lo]" + : [lo]"=a" (product), [hi]"=d" (tmp) + : "0" (delta), [mul_frac]"rm"((uint64_t)mul_frac)); + } +#else +#error "pvclock: unsupported x86 architecture?" +#endif + + return (product); +} + +static uint64_t +pvclock_get_nsec_offset(struct pvclock_vcpu_time_info *ti) +{ + uint64_t delta; + + delta = rdtsc() - ti->tsc_timestamp; + + return (pvclock_scale_delta(delta, ti->tsc_to_system_mul, + ti->tsc_shift)); +} + +static void +pvclock_read_time_info(struct pvclock_vcpu_time_info *ti, + uint64_t *cycles, uint8_t *flags) +{ + uint32_t version; + + do { + version = ti->version; + rmb(); + *cycles = ti->system_time + pvclock_get_nsec_offset(ti); + *flags = ti->flags; + rmb(); + } while ((ti->version & 1) != 0 || ti->version != version); +} + +static void +pvclock_read_wall_clock(struct pvclock_wall_clock *wc, uint32_t *sec, + uint32_t *nsec) +{ + uint32_t version; + + do { + version = wc->version; + rmb(); + *sec = wc->sec; + *nsec = wc->nsec; + rmb(); + } while ((wc->version & 1) != 0 || wc->version != version); +} + +uint64_t +pvclock_get_timecount(struct pvclock_vcpu_time_info *ti) +{ + uint64_t now, last; + uint8_t flags; + + pvclock_read_time_info(ti, &now, &flags); + + if (flags & PVCLOCK_FLAG_TSC_STABLE) + return (now); + + /* + * Enforce a monotonically increasing clock time across all VCPUs. + * If our time is too old, use the last time and return. Otherwise, + * try to update the last time. + */ + do { + last = atomic_load_acq_64(&pvclock_last_cycles); + if (last > now) + return (last); + } while (!atomic_cmpset_64(&pvclock_last_cycles, last, now)); + + return (now); +} + +void +pvclock_get_wallclock(struct pvclock_wall_clock *wc, struct timespec *ts) +{ + uint32_t sec, nsec; + + pvclock_read_wall_clock(wc, &sec, &nsec); + ts->tv_sec = sec; + ts->tv_nsec = nsec; +} |