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| author | Peter Zijlstra <peterz@infradead.org> | 2023-05-19 13:21:07 +0300 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2023-06-05 22:11:07 +0300 |
| commit | 9397fa2ea3e7634f61da1ab76b9eb88ba04dfdfc (patch) | |
| tree | f7e754cc61e0394b21845060b3f41f6b5f7bc450 /arch/x86/kvm/x86.c | |
| parent | 77750f78b0b3247c64b9821b49158cafe0506880 (diff) | |
| download | linux-9397fa2ea3e7634f61da1ab76b9eb88ba04dfdfc.tar.xz | |
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 'arch/x86/kvm/x86.c')
| -rw-r--r-- | arch/x86/kvm/x86.c | 7 |
1 files changed, 3 insertions, 4 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index ceb7c5e9cf9e..99d97ba6104f 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2799,14 +2799,13 @@ static u64 read_tsc(void) static inline u64 vgettsc(struct pvclock_clock *clock, u64 *tsc_timestamp, int *mode) { - long v; u64 tsc_pg_val; + long v; switch (clock->vclock_mode) { case VDSO_CLOCKMODE_HVCLOCK: - tsc_pg_val = hv_read_tsc_page_tsc(hv_get_tsc_page(), - tsc_timestamp); - if (tsc_pg_val != U64_MAX) { + if (hv_read_tsc_page_tsc(hv_get_tsc_page(), + tsc_timestamp, &tsc_pg_val)) { /* TSC page valid */ *mode = VDSO_CLOCKMODE_HVCLOCK; v = (tsc_pg_val - clock->cycle_last) & |