diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2023-05-19 12:21:07 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2023-06-05 21:11:07 +0200 |
| commit | 9397fa2ea3e7634f61da1ab76b9eb88ba04dfdfc (patch) | |
| tree | f7e754cc61e0394b21845060b3f41f6b5f7bc450 /include/clocksource | |
| parent | 77750f78b0b3247c64b9821b49158cafe0506880 (diff) | |
clocksource: hyper-v: Adjust hv_read_tsc_page_tsc() to avoid special casing U64_MAX
Currently hv_read_tsc_page_tsc() (ab)uses the (valid) time value of
U64_MAX as an error return. This breaks the clean wrap-around of the
clock.
Modify the function signature to return a boolean state and provide
another u64 pointer to store the actual time on success. This obviates
the need to steal one time value and restores the full counter width.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Michael Kelley <mikelley@microsoft.com> # Hyper-V
Link: https://lore.kernel.org/r/20230519102715.775630881@infradead.org
Diffstat (limited to 'include/clocksource')
| -rw-r--r-- | include/clocksource/hyperv_timer.h | 24 |
1 files changed, 9 insertions, 15 deletions
diff --git a/include/clocksource/hyperv_timer.h b/include/clocksource/hyperv_timer.h index 536f897375d0..6cdc873ac907 100644 --- a/include/clocksource/hyperv_timer.h +++ b/include/clocksource/hyperv_timer.h @@ -38,8 +38,9 @@ extern void hv_remap_tsc_clocksource(void); extern unsigned long hv_get_tsc_pfn(void); extern struct ms_hyperv_tsc_page *hv_get_tsc_page(void); -static inline notrace u64 -hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg, u64 *cur_tsc) +static __always_inline bool +hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg, + u64 *cur_tsc, u64 *time) { u64 scale, offset; u32 sequence; @@ -63,7 +64,7 @@ hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg, u64 *cur_tsc) do { sequence = READ_ONCE(tsc_pg->tsc_sequence); if (!sequence) - return U64_MAX; + return false; /* * Make sure we read sequence before we read other values from * TSC page. @@ -82,15 +83,8 @@ hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg, u64 *cur_tsc) } while (READ_ONCE(tsc_pg->tsc_sequence) != sequence); - return mul_u64_u64_shr(*cur_tsc, scale, 64) + offset; -} - -static inline notrace u64 -hv_read_tsc_page(const struct ms_hyperv_tsc_page *tsc_pg) -{ - u64 cur_tsc; - - return hv_read_tsc_page_tsc(tsc_pg, &cur_tsc); + *time = mul_u64_u64_shr(*cur_tsc, scale, 64) + offset; + return true; } #else /* CONFIG_HYPERV_TIMER */ @@ -104,10 +98,10 @@ static inline struct ms_hyperv_tsc_page *hv_get_tsc_page(void) return NULL; } -static inline u64 hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg, - u64 *cur_tsc) +static __always_inline bool +hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg, u64 *cur_tsc, u64 *time) { - return U64_MAX; + return false; } static inline int hv_stimer_cleanup(unsigned int cpu) { return 0; } |