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KVM: Make kvm host use the paravirt clocksource structs

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This patch updates the kvm host code to use the pvclock structs.
It also makes the paravirt clock compatible with Xen.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
This commit is contained in:
Gerd Hoffmann 2008-06-03 16:17:31 +02:00 committed by Avi Kivity
parent 1c7b67f757
commit 50d0a0f987
2 changed files with 65 additions and 14 deletions
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75
arch/x86/kvm/x86.c
View file

@ -492,8 +492,8 @@ static int do_set_msr(struct kvm_vcpu *vcpu, unsigned index, u64 *data)
static void kvm_write_wall_clock(struct kvm *kvm, gpa_t wall_clock)
{
static int version;
struct kvm_wall_clock wc;
struct timespec wc_ts;
struct pvclock_wall_clock wc;
struct timespec now, sys, boot;
if (!wall_clock)
return;
@ -502,10 +502,19 @@ static void kvm_write_wall_clock(struct kvm *kvm, gpa_t wall_clock)
kvm_write_guest(kvm, wall_clock, &version, sizeof(version));
wc_ts = current_kernel_time();
wc.wc_sec = wc_ts.tv_sec;
wc.wc_nsec = wc_ts.tv_nsec;
wc.wc_version = version;
/*
* The guest calculates current wall clock time by adding
* system time (updated by kvm_write_guest_time below) to the
* wall clock specified here. guest system time equals host
* system time for us, thus we must fill in host boot time here.
*/
now = current_kernel_time();
ktime_get_ts(&sys);
boot = ns_to_timespec(timespec_to_ns(&now) - timespec_to_ns(&sys));
wc.sec = boot.tv_sec;
wc.nsec = boot.tv_nsec;
wc.version = version;
kvm_write_guest(kvm, wall_clock, &wc, sizeof(wc));
@ -513,6 +522,45 @@ static void kvm_write_wall_clock(struct kvm *kvm, gpa_t wall_clock)
kvm_write_guest(kvm, wall_clock, &version, sizeof(version));
}
static uint32_t div_frac(uint32_t dividend, uint32_t divisor)
{
uint32_t quotient, remainder;
/* Don't try to replace with do_div(), this one calculates
* "(dividend << 32) / divisor" */
__asm__ ( "divl %4"
: "=a" (quotient), "=d" (remainder)
: "0" (0), "1" (dividend), "r" (divisor) );
return quotient;
}
static void kvm_set_time_scale(uint32_t tsc_khz, struct pvclock_vcpu_time_info *hv_clock)
{
uint64_t nsecs = 1000000000LL;
int32_t shift = 0;
uint64_t tps64;
uint32_t tps32;
tps64 = tsc_khz * 1000LL;
while (tps64 > nsecs*2) {
tps64 >>= 1;
shift--;
}
tps32 = (uint32_t)tps64;
while (tps32 <= (uint32_t)nsecs) {
tps32 <<= 1;
shift++;
}
hv_clock->tsc_shift = shift;
hv_clock->tsc_to_system_mul = div_frac(nsecs, tps32);
pr_debug("%s: tsc_khz %u, tsc_shift %d, tsc_mul %u\n",
__FUNCTION__, tsc_khz, hv_clock->tsc_shift,
hv_clock->tsc_to_system_mul);
}
static void kvm_write_guest_time(struct kvm_vcpu *v)
{
struct timespec ts;
@ -523,6 +571,11 @@ static void kvm_write_guest_time(struct kvm_vcpu *v)
if ((!vcpu->time_page))
return;
if (unlikely(vcpu->hv_clock_tsc_khz != tsc_khz)) {
kvm_set_time_scale(tsc_khz, &vcpu->hv_clock);
vcpu->hv_clock_tsc_khz = tsc_khz;
}
/* Keep irq disabled to prevent changes to the clock */
local_irq_save(flags);
kvm_get_msr(v, MSR_IA32_TIME_STAMP_COUNTER,
@ -537,14 +590,14 @@ static void kvm_write_guest_time(struct kvm_vcpu *v)
/*
* The interface expects us to write an even number signaling that the
* update is finished. Since the guest won't see the intermediate
* state, we just write "2" at the end
* state, we just increase by 2 at the end.
*/
vcpu->hv_clock.version = 2;
vcpu->hv_clock.version += 2;
shared_kaddr = kmap_atomic(vcpu->time_page, KM_USER0);
memcpy(shared_kaddr + vcpu->time_offset, &vcpu->hv_clock,
sizeof(vcpu->hv_clock));
sizeof(vcpu->hv_clock));
kunmap_atomic(shared_kaddr, KM_USER0);
@ -599,10 +652,6 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
/* ...but clean it before doing the actual write */
vcpu->arch.time_offset = data & ~(PAGE_MASK | 1);
vcpu->arch.hv_clock.tsc_to_system_mul =
clocksource_khz2mult(tsc_khz, 22);
vcpu->arch.hv_clock.tsc_shift = 22;
down_read(&current->mm->mmap_sem);
vcpu->arch.time_page =
gfn_to_page(vcpu->kvm, data >> PAGE_SHIFT);

4
include/asm-x86/kvm_host.h
View file

@ -18,6 +18,7 @@
#include <linux/kvm_para.h>
#include <linux/kvm_types.h>
#include <asm/pvclock-abi.h>
#include <asm/desc.h>
#define KVM_MAX_VCPUS 16
@ -282,7 +283,8 @@ struct kvm_vcpu_arch {
struct x86_emulate_ctxt emulate_ctxt;
gpa_t time;
struct kvm_vcpu_time_info hv_clock;
struct pvclock_vcpu_time_info hv_clock;
unsigned int hv_clock_tsc_khz;
unsigned int time_offset;
struct page *time_page;
};