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KVM: ia64: SN2 adjust emulated ITC frequency to match RTC frequency

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On SN2 do not pass down the real ITC frequency, but rather patch the
values to match the SN2 RTC frequency.

Signed-off-by: Jes Sorensen <jes@sgi.com>
Acked-by: Xiantao Zhang <xiantao.zhang@intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Jes Sorensen 2009-02-25 10:38:54 -06:00 committed by Avi Kivity
parent c6c9fcdf0f
commit ce17c64373
1 changed files with 27 additions and 1 deletions
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28
arch/ia64/kvm/kvm_fw.c
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@ -21,6 +21,9 @@
#include <linux/kvm_host.h>
#include <linux/smp.h>
#include <asm/sn/addrs.h>
#include <asm/sn/clksupport.h>
#include <asm/sn/shub_mmr.h>
#include "vti.h"
#include "misc.h"
@ -188,12 +191,35 @@ static struct ia64_pal_retval pal_freq_base(struct kvm_vcpu *vcpu)
return result;
}
/*
* On the SGI SN2, the ITC isn't stable. Emulation backed by the SN2
* RTC is used instead. This function patches the ratios from SAL
* to match the RTC before providing them to the guest.
*/
static void sn2_patch_itc_freq_ratios(struct ia64_pal_retval *result)
{
struct pal_freq_ratio *ratio;
unsigned long sal_freq, sal_drift, factor;
result->status = ia64_sal_freq_base(SAL_FREQ_BASE_PLATFORM,
&sal_freq, &sal_drift);
ratio = (struct pal_freq_ratio *)&result->v2;
factor = ((sal_freq * 3) + (sn_rtc_cycles_per_second / 2)) /
sn_rtc_cycles_per_second;
ratio->num = 3;
ratio->den = factor;
}
static struct ia64_pal_retval pal_freq_ratios(struct kvm_vcpu *vcpu)
{
struct ia64_pal_retval result;
PAL_CALL(result, PAL_FREQ_RATIOS, 0, 0, 0);
if (vcpu->kvm->arch.is_sn2)
sn2_patch_itc_freq_ratios(&result);
return result;
}