include/asm/pvclock.h

0001 /* SPDX-License-Identifier: GPL-2.0 */
0002 #ifndef _ASM_X86_PVCLOCK_H
0003 #define _ASM_X86_PVCLOCK_H
0004
0005 #include <asm/clocksource.h>
0006 #include <asm/pvclock-abi.h>
0007
0008 /* some helper functions for xen and kvm pv clock sources */
0009 u64 pvclock_clocksource_read(struct pvclock_vcpu_time_info *src);
0010 u8 pvclock_read_flags(struct pvclock_vcpu_time_info *src);
0011 void pvclock_set_flags(u8 flags);
0012 unsigned long pvclock_tsc_khz(struct pvclock_vcpu_time_info *src);
0013 void pvclock_read_wallclock(struct pvclock_wall_clock *wall,
0014                 struct pvclock_vcpu_time_info *vcpu,
0015                 struct timespec64 *ts);
0016 void pvclock_resume(void);
0017
0018 void pvclock_touch_watchdogs(void);
0019
0020 static __always_inline
0021 unsigned pvclock_read_begin(const struct pvclock_vcpu_time_info *src)
0022 {
0023     unsigned version = src->version & ~1;
0024     /* Make sure that the version is read before the data. */
0025     virt_rmb();
0026     return version;
0027 }
0028
0029 static __always_inline
0030 bool pvclock_read_retry(const struct pvclock_vcpu_time_info *src,
0031             unsigned version)
0032 {
0033     /* Make sure that the version is re-read after the data. */
0034     virt_rmb();
0035     return unlikely(version != src->version);
0036 }
0037
0038 /*
0039  * Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction,
0040  * yielding a 64-bit result.
0041  */
0042 static inline u64 pvclock_scale_delta(u64 delta, u32 mul_frac, int shift)
0043 {
0044     u64 product;
0045 #ifdef __i386__
0046     u32 tmp1, tmp2;
0047 #else
0048     ulong tmp;
0049 #endif
0050
0051     if (shift < 0)
0052         delta >>= -shift;
0053     else
0054         delta <<= shift;
0055
0056 #ifdef __i386__
0057     __asm__ (
0058         "mul  %5       ; "
0059         "mov  %4,%%eax ; "
0060         "mov  %%edx,%4 ; "
0061         "mul  %5       ; "
0062         "xor  %5,%5    ; "
0063         "add  %4,%%eax ; "
0064         "adc  %5,%%edx ; "
0065         : "=A" (product), "=r" (tmp1), "=r" (tmp2)
0066         : "a" ((u32)delta), "1" ((u32)(delta >> 32)), "2" (mul_frac) );
0067 #elif defined(__x86_64__)
0068     __asm__ (
0069         "mulq %[mul_frac] ; shrd $32, %[hi], %[lo]"
0070         : [lo]"=a"(product),
0071           [hi]"=d"(tmp)
0072         : "0"(delta),
0073           [mul_frac]"rm"((u64)mul_frac));
0074 #else
0075 #error implement me!
0076 #endif
0077
0078     return product;
0079 }
0080
0081 static __always_inline
0082 u64 __pvclock_read_cycles(const struct pvclock_vcpu_time_info *src, u64 tsc)
0083 {
0084     u64 delta = tsc - src->tsc_timestamp;
0085     u64 offset = pvclock_scale_delta(delta, src->tsc_to_system_mul,
0086                          src->tsc_shift);
0087     return src->system_time + offset;
0088 }
0089
0090 struct pvclock_vsyscall_time_info {
0091     struct pvclock_vcpu_time_info pvti;
0092 } __attribute__((__aligned__(SMP_CACHE_BYTES)));
0093
0094 #define PVTI_SIZE sizeof(struct pvclock_vsyscall_time_info)
0095
0096 #ifdef CONFIG_PARAVIRT_CLOCK
0097 void pvclock_set_pvti_cpu0_va(struct pvclock_vsyscall_time_info *pvti);
0098 struct pvclock_vsyscall_time_info *pvclock_get_pvti_cpu0_va(void);
0099 #else
0100 static inline struct pvclock_vsyscall_time_info *pvclock_get_pvti_cpu0_va(void)
0101 {
0102     return NULL;
0103 }
0104 #endif
0105
0106 #endif /* _ASM_X86_PVCLOCK_H */