| Message ID | 20191218144233.15372-5-liuwe@microsoft.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Implement Hyper-V reference TSC based clock source | expand |
> -----Original Message----- > From: Wei Liu <wei.liu.xen@gmail.com> On Behalf Of Wei Liu > Sent: 18 December 2019 14:43 > To: Xen Development List <xen-devel@lists.xenproject.org> > Cc: Michael Kelley <mikelley@microsoft.com>; Durrant, Paul > <pdurrant@amazon.com>; Wei Liu <liuwe@microsoft.com>; Paul Durrant > <paul@xen.org>; Jan Beulich <jbeulich@suse.com>; Andrew Cooper > <andrew.cooper3@citrix.com>; Wei Liu <wl@xen.org>; Roger Pau Monné > <roger.pau@citrix.com> > Subject: [PATCH v2 4/6] x86/viridian: drop private copy of > HV_REFERENCE_TSC_PAGE in time.c > > Use the one defined in hyperv-tlfs.h instead. No functional change > intended. > > Signed-off-by: Wei Liu <liuwe@microsoft.com> > --- > xen/arch/x86/hvm/viridian/time.c | 30 +++++++++++------------------- > 1 file changed, 11 insertions(+), 19 deletions(-) > > diff --git a/xen/arch/x86/hvm/viridian/time.c > b/xen/arch/x86/hvm/viridian/time.c > index 6ddca29b29..33c15782e4 100644 > --- a/xen/arch/x86/hvm/viridian/time.c > +++ b/xen/arch/x86/hvm/viridian/time.c > @@ -13,19 +13,11 @@ > > #include <asm/apic.h> > #include <asm/event.h> > +#include <asm/guest/hyperv-tlfs.h> > #include <asm/hvm/support.h> > > #include "private.h" > > -typedef struct _HV_REFERENCE_TSC_PAGE > -{ > - uint32_t TscSequence; > - uint32_t Reserved1; > - uint64_t TscScale; > - int64_t TscOffset; > - uint64_t Reserved2[509]; > -} HV_REFERENCE_TSC_PAGE, *PHV_REFERENCE_TSC_PAGE; > - > static void update_reference_tsc(const struct domain *d, bool initialize) > { > struct viridian_domain *vd = d->arch.hvm.viridian; > @@ -41,18 +33,18 @@ static void update_reference_tsc(const struct domain > *d, bool initialize) > * This enlightenment must be disabled is the host TSC is not > invariant. > * However it is also disabled if vtsc is true (which means rdtsc is > * being emulated). This generally happens when guest TSC freq and > host > - * TSC freq don't match. The TscScale value could be adjusted to cope > + * TSC freq don't match. The tsc_scale value could be adjusted to > cope > * with this, allowing vtsc to be turned off, but support for this is > * not yet present in the hypervisor. Thus is it is possible that > * migrating a Windows VM between hosts of differing TSC frequencies > * may result in large differences in guest performance. Any jump in > * TSC due to migration down-time can, however, be compensated for by > - * setting the TscOffset value (see below). > + * setting the tsc_offset value (see below). > */ > if ( !host_tsc_is_safe() || d->arch.vtsc ) > { > /* > - * The specification states that valid values of TscSequence > range > + * The specification states that valid values of tsc_sequence > range > * from 0 to 0xFFFFFFFE. The value 0xFFFFFFFF is used to indicate > * this mechanism is no longer a reliable source of time and that > * the VM should fall back to a different source. > @@ -61,7 +53,7 @@ static void update_reference_tsc(const struct domain *d, > bool initialize) > * violate the spec. and rely on a value of 0 to indicate that > this > * enlightenment should no longer be used. > */ > - p->TscSequence = 0; > + p->tsc_sequence = 0; > > printk(XENLOG_G_INFO "d%d: VIRIDIAN REFERENCE_TSC: > invalidated\n", > d->domain_id); > @@ -72,29 +64,29 @@ static void update_reference_tsc(const struct domain > *d, bool initialize) > * The guest will calculate reference time according to the following > * formula: > * > - * ReferenceTime = ((RDTSC() * TscScale) >> 64) + TscOffset > + * ReferenceTime = ((RDTSC() * tsc_scale) >> 64) + tsc_offset > * > * Windows uses a 100ns tick, so we need a scale which is cpu > * ticks per 100ns shifted left by 64. > * The offset value is calculated on restore after migration and > * ensures that Windows will not see a large jump in ReferenceTime. > */ > - p->TscScale = ((10000ul << 32) / d->arch.tsc_khz) << 32; > - p->TscOffset = trc->off; > + p->tsc_scale = ((10000ul << 32) / d->arch.tsc_khz) << 32; > + p->tsc_offset = trc->off; > smp_wmb(); > > - seq = p->TscSequence + 1; > + seq = p->tsc_sequence + 1; > if ( seq == 0xFFFFFFFF || seq == 0 ) /* Avoid both 'invalid' values > */ > seq = 1; > > - p->TscSequence = seq; > + p->tsc_sequence = seq; > } > > /* > * The specification says: "The partition reference time is computed > * by the following formula: > * > - * ReferenceTime = ((VirtualTsc * TscScale) >> 64) + TscOffset > + * ReferenceTime = ((VirtualTsc * tsc_scale) >> 64) + tsc_offset I'd prefer keeping the CamelCase here as it's text lifted from the TLFS and not reliant on the header definitions. Paul > * > * The multiplication is a 64 bit multiplication, which results in a > * 128 bit number which is then shifted 64 times to the right to obtain > -- > 2.20.1
diff --git a/xen/arch/x86/hvm/viridian/time.c b/xen/arch/x86/hvm/viridian/time.c index 6ddca29b29..33c15782e4 100644 --- a/xen/arch/x86/hvm/viridian/time.c +++ b/xen/arch/x86/hvm/viridian/time.c @@ -13,19 +13,11 @@ #include <asm/apic.h> #include <asm/event.h> +#include <asm/guest/hyperv-tlfs.h> #include <asm/hvm/support.h> #include "private.h" -typedef struct _HV_REFERENCE_TSC_PAGE -{ - uint32_t TscSequence; - uint32_t Reserved1; - uint64_t TscScale; - int64_t TscOffset; - uint64_t Reserved2[509]; -} HV_REFERENCE_TSC_PAGE, *PHV_REFERENCE_TSC_PAGE; - static void update_reference_tsc(const struct domain *d, bool initialize) { struct viridian_domain *vd = d->arch.hvm.viridian; @@ -41,18 +33,18 @@ static void update_reference_tsc(const struct domain *d, bool initialize) * This enlightenment must be disabled is the host TSC is not invariant. * However it is also disabled if vtsc is true (which means rdtsc is * being emulated). This generally happens when guest TSC freq and host - * TSC freq don't match. The TscScale value could be adjusted to cope + * TSC freq don't match. The tsc_scale value could be adjusted to cope * with this, allowing vtsc to be turned off, but support for this is * not yet present in the hypervisor. Thus is it is possible that * migrating a Windows VM between hosts of differing TSC frequencies * may result in large differences in guest performance. Any jump in * TSC due to migration down-time can, however, be compensated for by - * setting the TscOffset value (see below). + * setting the tsc_offset value (see below). */ if ( !host_tsc_is_safe() || d->arch.vtsc ) { /* - * The specification states that valid values of TscSequence range + * The specification states that valid values of tsc_sequence range * from 0 to 0xFFFFFFFE. The value 0xFFFFFFFF is used to indicate * this mechanism is no longer a reliable source of time and that * the VM should fall back to a different source. @@ -61,7 +53,7 @@ static void update_reference_tsc(const struct domain *d, bool initialize) * violate the spec. and rely on a value of 0 to indicate that this * enlightenment should no longer be used. */ - p->TscSequence = 0; + p->tsc_sequence = 0; printk(XENLOG_G_INFO "d%d: VIRIDIAN REFERENCE_TSC: invalidated\n", d->domain_id); @@ -72,29 +64,29 @@ static void update_reference_tsc(const struct domain *d, bool initialize) * The guest will calculate reference time according to the following * formula: * - * ReferenceTime = ((RDTSC() * TscScale) >> 64) + TscOffset + * ReferenceTime = ((RDTSC() * tsc_scale) >> 64) + tsc_offset * * Windows uses a 100ns tick, so we need a scale which is cpu * ticks per 100ns shifted left by 64. * The offset value is calculated on restore after migration and * ensures that Windows will not see a large jump in ReferenceTime. */ - p->TscScale = ((10000ul << 32) / d->arch.tsc_khz) << 32; - p->TscOffset = trc->off; + p->tsc_scale = ((10000ul << 32) / d->arch.tsc_khz) << 32; + p->tsc_offset = trc->off; smp_wmb(); - seq = p->TscSequence + 1; + seq = p->tsc_sequence + 1; if ( seq == 0xFFFFFFFF || seq == 0 ) /* Avoid both 'invalid' values */ seq = 1; - p->TscSequence = seq; + p->tsc_sequence = seq; } /* * The specification says: "The partition reference time is computed * by the following formula: * - * ReferenceTime = ((VirtualTsc * TscScale) >> 64) + TscOffset + * ReferenceTime = ((VirtualTsc * tsc_scale) >> 64) + tsc_offset * * The multiplication is a 64 bit multiplication, which results in a * 128 bit number which is then shifted 64 times to the right to obtain
Use the one defined in hyperv-tlfs.h instead. No functional change intended. Signed-off-by: Wei Liu <liuwe@microsoft.com> --- xen/arch/x86/hvm/viridian/time.c | 30 +++++++++++------------------- 1 file changed, 11 insertions(+), 19 deletions(-)