Consolidate the guest-side and kvm-side definitions for Hyper-V TSC
reference page.
While at this, rewrite read_hv_clock_tsc using the existing helpers.
Signed-off-by: Roman Kagan <rka...@virtuozzo.com>
---
arch/x86/include/asm/kvm_host.h | 2 +-
arch/x86/include/uapi/asm/hyperv.h | 4 +--
drivers/hv/hyperv_vmbus.h | 8 ------
arch/x86/kvm/hyperv.c | 4 +--
drivers/hv/hv.c | 54 +++++++++++++++-----------------------
5 files changed, 26 insertions(+), 46 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 2e25038..2b85f49 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -713,7 +713,7 @@ struct kvm_hv {
u64 hv_crash_param[HV_X64_MSR_CRASH_PARAMS];
u64 hv_crash_ctl;
- HV_REFERENCE_TSC_PAGE tsc_ref;
+ struct hv_ref_tsc_page tsc_ref;
};
struct kvm_arch {
diff --git a/arch/x86/include/uapi/asm/hyperv.h
b/arch/x86/include/uapi/asm/hyperv.h
index 9b1a918..6098ab5 100644
--- a/arch/x86/include/uapi/asm/hyperv.h
+++ b/arch/x86/include/uapi/asm/hyperv.h
@@ -252,12 +252,12 @@
#define HV_STATUS_INVALID_CONNECTION_ID 18
#define HV_STATUS_INSUFFICIENT_BUFFERS 19
-typedef struct _HV_REFERENCE_TSC_PAGE {
+struct hv_ref_tsc_page {
__u32 tsc_sequence;
__u32 res1;
__u64 tsc_scale;
__s64 tsc_offset;
-} HV_REFERENCE_TSC_PAGE, *PHV_REFERENCE_TSC_PAGE;
+};
/* Define the number of synthetic interrupt sources. */
#define HV_SYNIC_SINT_COUNT (16)
diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index 0675b39..4516498 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -475,14 +475,6 @@ struct hv_context {
extern struct hv_context hv_context;
-struct ms_hyperv_tsc_page {
- volatile u32 tsc_sequence;
- u32 reserved1;
- volatile u64 tsc_scale;
- volatile s64 tsc_offset;
- u64 reserved2[509];
-};
-
struct hv_ring_buffer_debug_info {
u32 current_interrupt_mask;
u32 current_read_index;
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 1572c35..c7db112 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -806,7 +806,7 @@ static int kvm_hv_msr_set_crash_data(struct kvm_vcpu *vcpu,
* These two equivalencies are implemented in this function.
*/
static bool compute_tsc_page_parameters(struct pvclock_vcpu_time_info
*hv_clock,
- HV_REFERENCE_TSC_PAGE *tsc_ref)
+ struct hv_ref_tsc_page *tsc_ref)
{
u64 max_mul;
@@ -847,7 +847,7 @@ void kvm_hv_setup_tsc_page(struct kvm *kvm,
u64 gfn;
BUILD_BUG_ON(sizeof(tsc_seq) != sizeof(hv->tsc_ref.tsc_sequence));
- BUILD_BUG_ON(offsetof(HV_REFERENCE_TSC_PAGE, tsc_sequence) != 0);
+ BUILD_BUG_ON(offsetof(struct hv_ref_tsc_page, tsc_sequence) != 0);
if (!(hv->hv_tsc_page & HV_X64_MSR_TSC_REFERENCE_ENABLE))
return;
diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
index 446802a..a7256ec 100644
--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -137,41 +137,29 @@ EXPORT_SYMBOL_GPL(hv_do_hypercall);
#ifdef CONFIG_X86_64
static cycle_t read_hv_clock_tsc(struct clocksource *arg)
{
- cycle_t current_tick;
- struct ms_hyperv_tsc_page *tsc_pg = hv_context.tsc_page;
+ struct hv_ref_tsc_page *tsc_pg = hv_context.tsc_page;
+ u32 sequence;
+ u64 scale;
+ s64 offset;
+
+ do {
+ sequence = tsc_pg->tsc_sequence;
+ virt_rmb();
+
+ if (!sequence) {
+ /* fallback to MSR */
+ cycle_t current_tick;
+ rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
+ return current_tick;
+ }
- if (tsc_pg->tsc_sequence != 0) {
- /*
- * Use the tsc page to compute the value.
- */
+ scale = tsc_pg->tsc_scale;
+ offset = tsc_pg->tsc_offset;
- while (1) {
- cycle_t tmp;
- u32 sequence = tsc_pg->tsc_sequence;
- u64 cur_tsc;
- u64 scale = tsc_pg->tsc_scale;
- s64 offset = tsc_pg->tsc_offset;
-
- rdtscll(cur_tsc);
- /* current_tick = ((cur_tsc *scale) >> 64) + offset */
- asm("mulq %3"
- : "=d" (current_tick), "=a" (tmp)
- : "a" (cur_tsc), "r" (scale));
-
- current_tick += offset;
- if (tsc_pg->tsc_sequence == sequence)
- return current_tick;
-
- if (tsc_pg->tsc_sequence != 0)
- continue;
- /*
- * Fallback using MSR method.
- */
- break;
- }
- }
- rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
- return current_tick;
+ virt_rmb();
+ } while (tsc_pg->tsc_sequence != sequence);
+
+ return mul_u64_u64_shr(rdtsc_ordered(), scale, 64) + offset;
}
static struct clocksource hyperv_cs_tsc = {
--
2.9.3
