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 | 64 +++++++++++++++++++++++++++++++++++++++++++-
include/asm-x86/kvm_host.h | 5 +++
include/asm-x86/kvm_para.h | 5 +++
include/linux/kvm.h | 1 +
4 files changed, 74 insertions(+), 1 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 8a90403..d3fd920 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_PARAVIRT_CLOCK,
};
static unsigned num_msrs_to_save;
@@ -467,6 +468,50 @@ 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 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;
+
+ if (!vcpu->shared_info)
+ return;
+
+ /* Make the update of both version numbers visible to guest */
+ wc_args[0] = ++vcpu->wc_version;
+ kvm_write_guest(v->kvm, vcpu->shared_info + WC_OFFSET, wc_args,
+ sizeof(wc_args));
+ vcpu->hv_clock.version++;
+ kvm_write_guest(v->kvm, vcpu->clock_addr, &vcpu->hv_clock,
+ sizeof(vcpu->hv_clock));
+
+ /* 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;
+ wc_args[0] = ++vcpu->wc_version;
+
+ vcpu->hv_clock.system_time = ts.tv_nsec +
+ (NSEC_PER_SEC * (u64)ts.tv_sec);
+ vcpu->hv_clock.version++;
+
+ /* And finally, let the guest see them */
+ kvm_write_guest(v->kvm, vcpu->shared_info + WC_OFFSET, wc_args,
+ sizeof(wc_args));
+ kvm_write_guest(v->kvm, vcpu->clock_addr, &vcpu->hv_clock,
+ sizeof(vcpu->hv_clock));
+}
+
int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
{
@@ -494,6 +539,18 @@ 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_PARAVIRT_CLOCK: {
+ vcpu->arch.shared_info = data;
+
+ vcpu->arch.clock_addr = data + offsetof(struct vcpu_info, time)
+ + sizeof(struct vcpu_info) * vcpu->vcpu_id;
+
+ vcpu->arch.hv_clock.tsc_to_system_mul =
+ clocksource_khz2mult(tsc_khz, 22);
+ vcpu->arch.hv_clock.tsc_shift = 22;
+ kvm_write_guest_time(vcpu);
+ break;
+ }
default:
pr_unimpl(vcpu, "unhandled wrmsr: 0x%x data %llx\n", msr, data);
return 1;
@@ -553,6 +610,9 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64
*pdata)
data = vcpu->arch.shadow_efer;
break;
#endif
+ case MSR_PARAVIRT_CLOCK:
+ data = vcpu->arch.shared_info;
+ break;
default:
pr_unimpl(vcpu, "unhandled rdmsr: 0x%x\n", msr);
return 1;
@@ -680,6 +740,7 @@ 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 +798,7 @@ 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)
diff --git a/include/asm-x86/kvm_host.h b/include/asm-x86/kvm_host.h
index d6db0de..bbc4b51 100644
--- a/include/asm-x86/kvm_host.h
+++ b/include/asm-x86/kvm_host.h
@@ -261,6 +261,11 @@ struct kvm_vcpu_arch {
/* emulate context */
struct x86_emulate_ctxt emulate_ctxt;
+
+ struct vcpu_time_info hv_clock;
+ gpa_t shared_info;
+ gpa_t clock_addr; /* so we avoid computing it every time */
+ int wc_version;
};
struct kvm_mem_alias {
diff --git a/include/asm-x86/kvm_para.h b/include/asm-x86/kvm_para.h
index c6f3fd8..abe412a 100644
--- a/include/asm-x86/kvm_para.h
+++ b/include/asm-x86/kvm_para.h
@@ -1,5 +1,6 @@
#ifndef __X86_KVM_PARA_H
#define __X86_KVM_PARA_H
+#include <xen/interface/xen.h>
/* This CPUID returns the signature 'KVMKVMKVM' in ebx, ecx, and edx. It
* should be used to determine that a VM is running under KVM.
@@ -10,9 +11,13 @@
* paravirtualization, the appropriate feature bit should be checked.
*/
#define KVM_CPUID_FEATURES 0x40000001
+#define KVM_FEATURE_CLOCKSOURCE 0
+#define MSR_PARAVIRT_CLOCK 0x11
#ifdef __KERNEL__
#include <asm/processor.h>
+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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