[PATCH v3 2/7] x86/hyper-v: add a function to read both TSC and TSC page value simulateneously

Vitaly Kuznetsov
2018-01-16T18:31:26Z

This is going to be used from KVM code where we need to get both
TSC and TSC page value.

Nobody is supposed to use the function when Hyper-V code is compiled out,
just BUG().

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
arch/x86/hyperv/hv_init.c | 1 +
arch/x86/include/asm/mshyperv.h | 23 +++++++++++++++++++----
2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 21f9d53d9f00..1a6c63f721bc 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -37,6 +37,7 @@ struct ms_hyperv_tsc_page *hv_get_tsc_page(void)
{
return tsc_pg;
}
+EXPORT_SYMBOL_GPL(hv_get_tsc_page);

static u64 read_hv_clock_tsc(struct clocksource *arg)
{
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index 8bf450b13d9f..6b1d4ea78270 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -325,9 +325,10 @@ static inline void hyperv_setup_mmu_ops(void) {}

#ifdef CONFIG_HYPERV_TSCPAGE
struct ms_hyperv_tsc_page *hv_get_tsc_page(void);
-static inline u64 hv_read_tsc_page(const struct ms_hyperv_tsc_page *tsc_pg)
+static inline u64 hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg,
+ u64 *cur_tsc)
{
- u64 scale, offset, cur_tsc;
+ u64 scale, offset;
u32 sequence;

/*
@@ -358,7 +359,7 @@ static inline u64 hv_read_tsc_page(const struct ms_hyperv_tsc_page *tsc_pg)

scale = READ_ONCE(tsc_pg->tsc_scale);
offset = READ_ONCE(tsc_pg->tsc_offset);
- cur_tsc = rdtsc_ordered();
+ *cur_tsc = rdtsc_ordered();

/*
* Make sure we read sequence after we read all other values
@@ -368,7 +369,14 @@ static inline u64 hv_read_tsc_page(const struct ms_hyperv_tsc_page *tsc_pg)

} while (READ_ONCE(tsc_pg->tsc_sequence) != sequence);

- return mul_u64_u64_shr(cur_tsc, scale, 64) + offset;
+ return mul_u64_u64_shr(*cur_tsc, scale, 64) + offset;
+}
+
+static inline 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);
}

#else
@@ -376,5 +384,12 @@ 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)
+{
+ BUG();
+ return U64_MAX;
+}
#endif
#endif
--
2.14.3