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xen/21445-x86-tsc-handling-cleanups-v2.patch

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# HG changeset patch
# User Keir Fraser <keir.fraser@citrix.com>
# Date 1278094440 -3600
# Node ID a9c458ab90e4ecb25383456be653368ecd900ee4
# Parent 322468d5ab6ceca4afa21977a02f4492308d2ddc
x86: TSC handling cleanups (version 2)
"I am removing the tsc_scaled variable that is never actually used
because when tsc needs to be scaled vtsc is 1. I am also making this
more explicit in tsc_set_info. I am also removing hvm_domain.gtsc_khz
that is a duplicate of d->arch.tsc_khz. I am using scale_delta(delta,
&d->arch.ns_to_vtsc) to scale the tsc value before returning it to the
guest like in the pv case. I added a feature flag to specify that the
pvclock algorithm is safe to be used in an HVM guest so that the guest
can now use it without hanging."
Version 2 fixes a bug which breaks PV domU time.
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
xen-unstable changeset: 21445:c1ed00d49534
xen-unstable date: Sat May 22 06:31:47 2010 +0100
Index: xen-4.0.0-testing/xen/arch/x86/hvm/hvm.c
===================================================================
--- xen-4.0.0-testing.orig/xen/arch/x86/hvm/hvm.c
+++ xen-4.0.0-testing/xen/arch/x86/hvm/hvm.c
@@ -152,32 +152,6 @@ void hvm_set_rdtsc_exiting(struct domain
hvm_funcs.set_rdtsc_exiting(v, enable);
}
-int hvm_gtsc_need_scale(struct domain *d)
-{
- uint32_t gtsc_mhz, htsc_mhz;
-
- if ( d->arch.vtsc )
- return 0;
-
- gtsc_mhz = d->arch.hvm_domain.gtsc_khz / 1000;
- htsc_mhz = (uint32_t)cpu_khz / 1000;
-
- d->arch.hvm_domain.tsc_scaled = (gtsc_mhz && (gtsc_mhz != htsc_mhz));
- return d->arch.hvm_domain.tsc_scaled;
-}
-
-static u64 hvm_h2g_scale_tsc(struct vcpu *v, u64 host_tsc)
-{
- uint32_t gtsc_khz, htsc_khz;
-
- if ( !v->domain->arch.hvm_domain.tsc_scaled )
- return host_tsc;
-
- htsc_khz = cpu_khz;
- gtsc_khz = v->domain->arch.hvm_domain.gtsc_khz;
- return muldiv64(host_tsc, gtsc_khz, htsc_khz);
-}
-
void hvm_set_guest_tsc(struct vcpu *v, u64 guest_tsc)
{
uint64_t tsc;
@@ -185,11 +159,11 @@ void hvm_set_guest_tsc(struct vcpu *v, u
if ( v->domain->arch.vtsc )
{
tsc = hvm_get_guest_time(v);
+ tsc = gtime_to_gtsc(v->domain, tsc);
}
else
{
rdtscll(tsc);
- tsc = hvm_h2g_scale_tsc(v, tsc);
}
v->arch.hvm_vcpu.cache_tsc_offset = guest_tsc - tsc;
@@ -203,12 +177,12 @@ u64 hvm_get_guest_tsc(struct vcpu *v)
if ( v->domain->arch.vtsc )
{
tsc = hvm_get_guest_time(v);
+ tsc = gtime_to_gtsc(v->domain, tsc);
v->domain->arch.vtsc_kerncount++;
}
else
{
rdtscll(tsc);
- tsc = hvm_h2g_scale_tsc(v, tsc);
}
return tsc + v->arch.hvm_vcpu.cache_tsc_offset;
Index: xen-4.0.0-testing/xen/arch/x86/hvm/save.c
===================================================================
--- xen-4.0.0-testing.orig/xen/arch/x86/hvm/save.c
+++ xen-4.0.0-testing/xen/arch/x86/hvm/save.c
@@ -33,7 +33,7 @@ void arch_hvm_save(struct domain *d, str
hdr->cpuid = eax;
/* Save guest's preferred TSC. */
- hdr->gtsc_khz = d->arch.hvm_domain.gtsc_khz;
+ hdr->gtsc_khz = d->arch.tsc_khz;
}
int arch_hvm_load(struct domain *d, struct hvm_save_header *hdr)
@@ -62,8 +62,8 @@ int arch_hvm_load(struct domain *d, stru
/* Restore guest's preferred TSC frequency. */
if ( hdr->gtsc_khz )
- d->arch.hvm_domain.gtsc_khz = hdr->gtsc_khz;
- if ( hvm_gtsc_need_scale(d) )
+ d->arch.tsc_khz = hdr->gtsc_khz;
+ if ( d->arch.vtsc )
{
hvm_set_rdtsc_exiting(d, 1);
gdprintk(XENLOG_WARNING, "Domain %d expects freq %uMHz "
Index: xen-4.0.0-testing/xen/arch/x86/hvm/vpt.c
===================================================================
--- xen-4.0.0-testing.orig/xen/arch/x86/hvm/vpt.c
+++ xen-4.0.0-testing/xen/arch/x86/hvm/vpt.c
@@ -32,9 +32,6 @@ void hvm_init_guest_time(struct domain *
spin_lock_init(&pl->pl_time_lock);
pl->stime_offset = -(u64)get_s_time();
pl->last_guest_time = 0;
-
- d->arch.hvm_domain.gtsc_khz = cpu_khz;
- d->arch.hvm_domain.tsc_scaled = 0;
}
u64 hvm_get_guest_time(struct vcpu *v)
Index: xen-4.0.0-testing/xen/arch/x86/time.c
===================================================================
--- xen-4.0.0-testing.orig/xen/arch/x86/time.c
+++ xen-4.0.0-testing/xen/arch/x86/time.c
@@ -850,8 +850,13 @@ static void __update_vcpu_system_time(st
if ( d->arch.vtsc )
{
- u64 delta = max_t(s64, t->stime_local_stamp - d->arch.vtsc_offset, 0);
- tsc_stamp = scale_delta(delta, &d->arch.ns_to_vtsc);
+ u64 stime = t->stime_local_stamp;
+ if ( is_hvm_domain(d) )
+ {
+ struct pl_time *pl = &v->domain->arch.hvm_domain.pl_time;
+ stime += pl->stime_offset + v->arch.hvm_vcpu.stime_offset;
+ }
+ tsc_stamp = gtime_to_gtsc(d, stime);
}
else
{
@@ -874,6 +879,8 @@ static void __update_vcpu_system_time(st
_u.tsc_to_system_mul = t->tsc_scale.mul_frac;
_u.tsc_shift = (s8)t->tsc_scale.shift;
}
+ if ( is_hvm_domain(d) )
+ _u.tsc_timestamp += v->arch.hvm_vcpu.cache_tsc_offset;
/* Don't bother unless timestamp record has changed or we are forced. */
_u.version = u->version; /* make versions match for memcmp test */
@@ -1640,11 +1647,17 @@ struct tm wallclock_time(void)
* PV SoftTSC Emulation.
*/
+u64 gtime_to_gtsc(struct domain *d, u64 tsc)
+{
+ if ( !is_hvm_domain(d) )
+ tsc = max_t(s64, tsc - d->arch.vtsc_offset, 0);
+ return scale_delta(tsc, &d->arch.ns_to_vtsc);
+}
+
void pv_soft_rdtsc(struct vcpu *v, struct cpu_user_regs *regs, int rdtscp)
{
s_time_t now = get_s_time();
struct domain *d = v->domain;
- u64 delta;
spin_lock(&d->arch.vtsc_lock);
@@ -1660,8 +1673,7 @@ void pv_soft_rdtsc(struct vcpu *v, struc
spin_unlock(&d->arch.vtsc_lock);
- delta = max_t(s64, now - d->arch.vtsc_offset, 0);
- now = scale_delta(delta, &d->arch.ns_to_vtsc);
+ now = gtime_to_gtsc(d, now);
regs->eax = (uint32_t)now;
regs->edx = (uint32_t)(now >> 32);
@@ -1802,8 +1814,10 @@ void tsc_set_info(struct domain *d,
d->arch.vtsc_offset = get_s_time() - elapsed_nsec;
d->arch.tsc_khz = gtsc_khz ? gtsc_khz : cpu_khz;
set_time_scale(&d->arch.vtsc_to_ns, d->arch.tsc_khz * 1000 );
- /* use native TSC if initial host has safe TSC and not migrated yet */
- if ( host_tsc_is_safe() && incarnation == 0 )
+ /* use native TSC if initial host has safe TSC, has not migrated
+ * yet and tsc_khz == cpu_khz */
+ if ( host_tsc_is_safe() && incarnation == 0 &&
+ d->arch.tsc_khz == cpu_khz )
d->arch.vtsc = 0;
else
d->arch.ns_to_vtsc = scale_reciprocal(d->arch.vtsc_to_ns);
@@ -1828,7 +1842,7 @@ void tsc_set_info(struct domain *d,
}
d->arch.incarnation = incarnation + 1;
if ( is_hvm_domain(d) )
- hvm_set_rdtsc_exiting(d, d->arch.vtsc || hvm_gtsc_need_scale(d));
+ hvm_set_rdtsc_exiting(d, d->arch.vtsc);
}
/* vtsc may incur measurable performance degradation, diagnose with this */
Index: xen-4.0.0-testing/xen/common/kernel.c
===================================================================
--- xen-4.0.0-testing.orig/xen/common/kernel.c
+++ xen-4.0.0-testing/xen/common/kernel.c
@@ -243,6 +243,8 @@ DO(xen_version)(int cmd, XEN_GUEST_HANDL
fi.submap |= (1U << XENFEAT_mmu_pt_update_preserve_ad) |
(1U << XENFEAT_highmem_assist) |
(1U << XENFEAT_gnttab_map_avail_bits);
+ else
+ fi.submap |= (1U << XENFEAT_hvm_safe_pvclock);
#endif
break;
default:
Index: xen-4.0.0-testing/xen/include/asm-x86/hvm/domain.h
===================================================================
--- xen-4.0.0-testing.orig/xen/include/asm-x86/hvm/domain.h
+++ xen-4.0.0-testing/xen/include/asm-x86/hvm/domain.h
@@ -45,8 +45,6 @@ struct hvm_domain {
struct hvm_ioreq_page ioreq;
struct hvm_ioreq_page buf_ioreq;
- uint32_t gtsc_khz; /* kHz */
- bool_t tsc_scaled;
struct pl_time pl_time;
struct hvm_io_handler io_handler;
Index: xen-4.0.0-testing/xen/include/asm-x86/hvm/hvm.h
===================================================================
--- xen-4.0.0-testing.orig/xen/include/asm-x86/hvm/hvm.h
+++ xen-4.0.0-testing/xen/include/asm-x86/hvm/hvm.h
@@ -290,7 +290,6 @@ int hvm_event_needs_reinjection(uint8_t
uint8_t hvm_combine_hw_exceptions(uint8_t vec1, uint8_t vec2);
void hvm_set_rdtsc_exiting(struct domain *d, bool_t enable);
-int hvm_gtsc_need_scale(struct domain *d);
static inline int
hvm_cpu_prepare(unsigned int cpu)
Index: xen-4.0.0-testing/xen/include/asm-x86/time.h
===================================================================
--- xen-4.0.0-testing.orig/xen/include/asm-x86/time.h
+++ xen-4.0.0-testing/xen/include/asm-x86/time.h
@@ -60,6 +60,7 @@ uint64_t acpi_pm_tick_to_ns(uint64_t tic
uint64_t ns_to_acpi_pm_tick(uint64_t ns);
void pv_soft_rdtsc(struct vcpu *v, struct cpu_user_regs *regs, int rdtscp);
+u64 gtime_to_gtsc(struct domain *d, u64 tsc);
void tsc_set_info(struct domain *d, uint32_t tsc_mode, uint64_t elapsed_nsec,
uint32_t gtsc_khz, uint32_t incarnation);
Index: xen-4.0.0-testing/xen/include/public/features.h
===================================================================
--- xen-4.0.0-testing.orig/xen/include/public/features.h
+++ xen-4.0.0-testing/xen/include/public/features.h
@@ -68,6 +68,9 @@
*/
#define XENFEAT_gnttab_map_avail_bits 7
+/* x86: pvclock algorithm is safe to use on HVM */
+#define XENFEAT_hvm_safe_pvclock 9
+
#define XENFEAT_NR_SUBMAPS 1
#endif /* __XEN_PUBLIC_FEATURES_H__ */
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