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.
The area is binary compatible with xen, as we use the same shadow_info
structure.
Signed-off-by: Glauber de Oliveira Costa <[EMAIL PROTECTED]>
---
arch/x86/kvm/x86.c | 79 +++++++++++++++++++++++++++++++++++++++++++-
include/asm-x86/kvm_host.h | 4 ++
include/asm-x86/kvm_para.h | 37 ++++++++++++++++++++
include/linux/kvm.h | 1 +
4 files changed, 120 insertions(+), 1 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 8a90403..53b5692 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -19,6 +19,7 @@
#include "irq.h"
#include "mmu.h"
+#include <linux/clocksource.h>
#include <linux/kvm.h>
#include <linux/fs.h>
#include <linux/vmalloc.h>
@@ -412,7 +413,7 @@ static u32 msrs_to_save[] = {
#ifdef CONFIG_X86_64
MSR_CSTAR, MSR_KERNEL_GS_BASE, MSR_SYSCALL_MASK, MSR_LSTAR,
#endif
- MSR_IA32_TIME_STAMP_COUNTER,
+ MSR_IA32_TIME_STAMP_COUNTER, MSR_KVM_PARAVIRT_CLOCK,
};
static unsigned num_msrs_to_save;
@@ -467,6 +468,60 @@ static int do_set_msr(struct kvm_vcpu *vcpu, unsigned
index, u64 *data)
return kvm_set_msr(vcpu, index, *data);
}
+#define WC_OFFSET offsetof(struct xen_shared_info, wc_version)
+
+static void kvm_write_guest_time(struct kvm_vcpu *v)
+{
+ struct timespec ts, wc_ts;
+ int wc_args[3]; /* version, wc_sec, wc_nsec */
+ unsigned long flags;
+ struct kvm_vcpu_arch *vcpu = &v->arch;
+ struct xen_shared_info *shared_kaddr;
+
+ if ((!vcpu->shared_page))
+ return;
+
+ /* Keep irq disabled to prevent changes to the clock */
+ local_irq_save(flags);
+ kvm_get_msr(v, MSR_IA32_TIME_STAMP_COUNTER,
+ &vcpu->hv_clock.tsc_timestamp);
+ wc_ts = current_kernel_time();
+ ktime_get_ts(&ts);
+ local_irq_restore(flags);
+
+ /* With all the info we got, fill in the values */
+ wc_args[1] = wc_ts.tv_sec;
+ wc_args[2] = wc_ts.tv_nsec;
+
+ vcpu->hv_clock.system_time = ts.tv_nsec +
+ (NSEC_PER_SEC * (u64)ts.tv_sec);
+ /*
+ * The interface expects us to write an even number signaling that the
+ * update is finished. Since the guest won't see the intermediate
states,
+ * we just write "2" at the end
+ */
+ wc_args[0] = 2;
+ vcpu->hv_clock.version = 2;
+
+ preempt_disable();
+
+ shared_kaddr = kmap_atomic(vcpu->shared_page, KM_USER0);
+
+ /*
+ * We could write everything at once, but it can break future
+ * implementations. We're just a tiny and lonely clock, so let's
+ * write only what matters here
+ */
+ memcpy(&shared_kaddr->wc_version, wc_args, sizeof(wc_args));
+ memcpy(&shared_kaddr->vcpu_info[v->vcpu_id].time, &vcpu->hv_clock,
+ sizeof(vcpu->hv_clock));
+
+ kunmap_atomic(shared_kaddr, KM_USER0);
+ preempt_enable();
+
+ mark_page_dirty(v->kvm, vcpu->shared_info >> PAGE_SHIFT);
+}
+
int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
{
@@ -494,6 +549,20 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64
data)
case MSR_IA32_MISC_ENABLE:
vcpu->arch.ia32_misc_enable_msr = data;
break;
+ case MSR_KVM_PARAVIRT_CLOCK: {
+ vcpu->arch.shared_info = data;
+
+ vcpu->arch.hv_clock.tsc_to_system_mul =
+ clocksource_khz2mult(tsc_khz, 22);
+ vcpu->arch.hv_clock.tsc_shift = 22;
+
+ down_write(¤t->mm->mmap_sem);
+ vcpu->arch.shared_page = gfn_to_page(vcpu->kvm, data >>
PAGE_SHIFT);
+ up_write(¤t->mm->mmap_sem);
+ if (is_error_page(vcpu->arch.shared_page))
+ vcpu->arch.shared_page = NULL;
+ break;
+ }
default:
pr_unimpl(vcpu, "unhandled wrmsr: 0x%x data %llx\n", msr, data);
return 1;
@@ -553,6 +622,10 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64
*pdata)
data = vcpu->arch.shadow_efer;
break;
#endif
+ case MSR_KVM_PARAVIRT_CLOCK:
+ data = vcpu->arch.shared_info;
+ break;
+
default:
pr_unimpl(vcpu, "unhandled rdmsr: 0x%x\n", msr);
return 1;
@@ -680,6 +753,7 @@ int kvm_dev_ioctl_check_extension(long ext)
case KVM_CAP_USER_MEMORY:
case KVM_CAP_SET_TSS_ADDR:
case KVM_CAP_EXT_CPUID:
+ case KVM_CAP_CLOCKSOURCE:
r = 1;
break;
case KVM_CAP_VAPIC:
@@ -737,6 +811,7 @@ out:
void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
{
kvm_x86_ops->vcpu_load(vcpu, cpu);
+ kvm_write_guest_time(vcpu);
}
void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
@@ -3190,6 +3265,8 @@ static void kvm_free_vcpus(struct kvm *kvm)
kvm_unload_vcpu_mmu(kvm->vcpus[i]);
for (i = 0; i < KVM_MAX_VCPUS; ++i) {
if (kvm->vcpus[i]) {
+ if (kvm->vcpus[i]->arch.shared_page)
+
kvm_release_page_dirty(kvm->vcpus[i]->arch.shared_page);
kvm_arch_vcpu_free(kvm->vcpus[i]);
kvm->vcpus[i] = NULL;
}
diff --git a/include/asm-x86/kvm_host.h b/include/asm-x86/kvm_host.h
index d6db0de..9a66b90 100644
--- a/include/asm-x86/kvm_host.h
+++ b/include/asm-x86/kvm_host.h
@@ -261,6 +261,10 @@ struct kvm_vcpu_arch {
/* emulate context */
struct x86_emulate_ctxt emulate_ctxt;
+
+ struct xen_vcpu_time_info hv_clock;
+ gpa_t shared_info;
+ struct page *shared_page;
};
struct kvm_mem_alias {
diff --git a/include/asm-x86/kvm_para.h b/include/asm-x86/kvm_para.h
index c6f3fd8..145107d 100644
--- a/include/asm-x86/kvm_para.h
+++ b/include/asm-x86/kvm_para.h
@@ -10,10 +10,47 @@
* paravirtualization, the appropriate feature bit should be checked.
*/
#define KVM_CPUID_FEATURES 0x40000001
+#define KVM_FEATURE_CLOCKSOURCE 0
+
+#define MSR_KVM_PARAVIRT_CLOCK 0x11
#ifdef __KERNEL__
#include <asm/processor.h>
+/* xen binary-compatible interfaces. See xen headers for details */
+struct xen_vcpu_time_info {
+ uint32_t version;
+ uint32_t pad0;
+ uint64_t tsc_timestamp;
+ uint64_t system_time;
+ uint32_t tsc_to_system_mul;
+ int8_t tsc_shift;
+ int8_t pad1[3];
+};
+
+struct xen_vcpu_info {
+ uint8_t pad[32];
+ struct xen_vcpu_time_info time;
+};
+
+#define XEN_MAX_VIRT_CPUS 32
+
+struct xen_shared_info {
+ struct xen_vcpu_info vcpu_info[XEN_MAX_VIRT_CPUS];
+
+ unsigned long evt[2];
+
+ uint32_t wc_version; /* Version counter: see vcpu_time_info_t. */
+ uint32_t wc_sec; /* Secs 00:00:00 UTC, Jan 1, 1970. */
+ uint32_t wc_nsec; /* Nsecs 00:00:00 UTC, Jan 1, 1970. */
+
+ unsigned long pad[12];
+};
+
+
+extern void kvmclock_init(void);
+
+
/* This instruction is vmcall. On non-VT architectures, it will generate a
* trap that we will then rewrite to the appropriate instruction.
*/
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 4de4fd2..78ce53f 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -232,6 +232,7 @@ struct kvm_vapic_addr {
#define KVM_CAP_SET_TSS_ADDR 4
#define KVM_CAP_EXT_CPUID 5
#define KVM_CAP_VAPIC 6
+#define KVM_CAP_CLOCKSOURCE 7
/*
* ioctls for VM fds
--
1.5.0.6
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