[PATCH 2/3] kvmclock - the host part.

Glauber de Oliveira Costa
2007-11-08T21:40:37Z

This is the host part of kvm clocksource implementation. As it does
not include clockevents, it is a fairly simple implementation. We
only have to register a per-vcpu area, and start writting to it periodically.

Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com>
---
drivers/kvm/kvm_main.c | 1 +
drivers/kvm/x86.c | 32 ++++++++++++++++++++++++++++++++
drivers/kvm/x86.h | 4 ++++
3 files changed, 37 insertions(+), 0 deletions(-)

diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index d095002..c2c79b8 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -1243,6 +1243,7 @@ static long kvm_dev_ioctl(struct file *filp,
case KVM_CAP_MMU_SHADOW_CACHE_CONTROL:
case KVM_CAP_USER_MEMORY:
case KVM_CAP_SET_TSS_ADDR:
+ case KVM_CAP_CLOCKSOURCE:
r = 1;
break;
default:
diff --git a/drivers/kvm/x86.c b/drivers/kvm/x86.c
index e905d46..ef31fed 100644
--- a/drivers/kvm/x86.c
+++ b/drivers/kvm/x86.c
@@ -19,6 +19,7 @@
#include "segment_descriptor.h"
#include "irq.h"

+#include <linux/clocksource.h>
#include <linux/kvm.h>
#include <linux/fs.h>
#include <linux/vmalloc.h>
@@ -1628,6 +1629,28 @@ int kvm_emulate_halt(struct kvm_vcpu *vcpu)
}
EXPORT_SYMBOL_GPL(kvm_emulate_halt);

+static void kvm_write_guest_time(struct kvm_vcpu *vcpu)
+{
+ struct timespec ts;
+ int r;
+
+ if (!vcpu->clock_gpa)
+ return;
+
+ /* Updates version to the next odd number, indicating we're writing */
+ vcpu->hv_clock.version++;
+ kvm_write_guest(vcpu->kvm, vcpu->clock_gpa, &vcpu->hv_clock, PAGE_SIZE);
+
+ kvm_get_msr(vcpu, MSR_IA32_TIME_STAMP_COUNTER,
+ &vcpu->hv_clock.last_tsc);
+
+ ktime_get_ts(&ts);
+ vcpu->hv_clock.now_ns = ts.tv_nsec + (NSEC_PER_SEC * (u64)ts.tv_sec);
+ vcpu->hv_clock.wc_sec = get_seconds();
+ vcpu->hv_clock.version++;
+ kvm_write_guest(vcpu->kvm, vcpu->clock_gpa, &vcpu->hv_clock, PAGE_SIZE);
+}
+
int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
{
unsigned long nr, a0, a1, a2, a3, ret;
@@ -1648,7 +1671,15 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
a3 &= 0xFFFFFFFF;
}

+ ret = 0;
switch (nr) {
+ case KVM_HCALL_REGISTER_CLOCK:
+
+ vcpu->clock_gpa = a0 << PAGE_SHIFT;
+ vcpu->hv_clock.tsc_mult = clocksource_khz2mult(tsc_khz, 22);
+
+ break;
+
default:
ret = -KVM_ENOSYS;
break;
@@ -1924,6 +1955,7 @@ out:
goto preempted;
}

+ kvm_write_guest_time(vcpu);
post_kvm_run_save(vcpu, kvm_run);

return r;
diff --git a/drivers/kvm/x86.h b/drivers/kvm/x86.h
index 663b822..fd77b66 100644
--- a/drivers/kvm/x86.h
+++ b/drivers/kvm/x86.h
@@ -83,6 +83,10 @@ struct kvm_vcpu {
/* emulate context */

struct x86_emulate_ctxt emulate_ctxt;
+
+ struct kvm_hv_clock_s hv_clock;
+ gpa_t clock_gpa; /* guest frame number, physical addr */
+
};

int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t gva, u32 error_code);
--
1.5.0.6