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Date: Mon, 31 Mar 2008 17:37:16 +0300
From: Avi Kivity <avi@...ranet.com>
To: kvm-devel@...ts.sourceforge.net
Cc: linux-kernel@...r.kernel.org,
Glauber de Oliveira Costa <gcosta@...hat.com>
Subject: [PATCH 32/40] KVM: paravirtualized clocksource: host part
From: Glauber de Oliveira Costa <gcosta@...hat.com>
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 writing to it periodically.
The area is binary compatible with xen, as we use the same shadow_info
structure.
[marcelo: fix bad_page on MSR_KVM_SYSTEM_TIME]
[avi: save full value of the msr, even if enable bit is clear]
[avi: clear previous value of time_page]
Signed-off-by: Glauber de Oliveira Costa <gcosta@...hat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@...hat.com>
Signed-off-by: Avi Kivity <avi@...ranet.com>
---
arch/x86/kvm/x86.c | 113 +++++++++++++++++++++++++++++++++++++++++++-
include/asm-x86/kvm_host.h | 7 +++
include/asm-x86/kvm_para.h | 25 ++++++++++
include/linux/kvm.h | 1 +
4 files changed, 145 insertions(+), 1 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 0c910c7..256c0fc 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>
@@ -424,7 +425,7 @@ 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_SYSTEM_TIME, MSR_KVM_WALL_CLOCK,
};
static unsigned num_msrs_to_save;
@@ -482,6 +483,70 @@ static int do_set_msr(struct kvm_vcpu *vcpu, unsigned index, u64 *data)
return kvm_set_msr(vcpu, index, *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;
+
+ if (!wall_clock)
+ return;
+
+ version++;
+
+ down_read(&kvm->slots_lock);
+ 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;
+
+ kvm_write_guest(kvm, wall_clock, &wc, sizeof(wc));
+
+ version++;
+ kvm_write_guest(kvm, wall_clock, &version, sizeof(version));
+ up_read(&kvm->slots_lock);
+}
+
+static void kvm_write_guest_time(struct kvm_vcpu *v)
+{
+ struct timespec ts;
+ unsigned long flags;
+ struct kvm_vcpu_arch *vcpu = &v->arch;
+ void *shared_kaddr;
+
+ if ((!vcpu->time_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);
+ ktime_get_ts(&ts);
+ local_irq_restore(flags);
+
+ /* With all the info we got, fill in the values */
+
+ 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
+ * state, we just write "2" at the end
+ */
+ 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));
+
+ kunmap_atomic(shared_kaddr, KM_USER0);
+
+ mark_page_dirty(v->kvm, vcpu->time >> PAGE_SHIFT);
+}
+
int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
{
@@ -511,6 +576,44 @@ 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_WALL_CLOCK:
+ vcpu->kvm->arch.wall_clock = data;
+ kvm_write_wall_clock(vcpu->kvm, data);
+ break;
+ case MSR_KVM_SYSTEM_TIME: {
+ if (vcpu->arch.time_page) {
+ kvm_release_page_dirty(vcpu->arch.time_page);
+ vcpu->arch.time_page = NULL;
+ }
+
+ vcpu->arch.time = data;
+
+ /* we verify if the enable bit is set... */
+ if (!(data & 1))
+ break;
+
+ /* ...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(¤t->mm->mmap_sem);
+ down_read(&vcpu->kvm->slots_lock);
+ vcpu->arch.time_page =
+ gfn_to_page(vcpu->kvm, data >> PAGE_SHIFT);
+ up_read(&vcpu->kvm->slots_lock);
+ up_read(¤t->mm->mmap_sem);
+
+ if (is_error_page(vcpu->arch.time_page)) {
+ kvm_release_page_clean(vcpu->arch.time_page);
+ vcpu->arch.time_page = NULL;
+ }
+
+ kvm_write_guest_time(vcpu);
+ break;
+ }
default:
pr_unimpl(vcpu, "unhandled wrmsr: 0x%x data %llx\n", msr, data);
return 1;
@@ -569,6 +672,12 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
case MSR_EFER:
data = vcpu->arch.shadow_efer;
break;
+ case MSR_KVM_WALL_CLOCK:
+ data = vcpu->kvm->arch.wall_clock;
+ break;
+ case MSR_KVM_SYSTEM_TIME:
+ data = vcpu->arch.time;
+ break;
default:
pr_unimpl(vcpu, "unhandled rdmsr: 0x%x\n", msr);
return 1;
@@ -696,6 +805,7 @@ 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:
@@ -771,6 +881,7 @@ 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 da61255..0c429c8 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;
+
+ gpa_t time;
+ struct kvm_vcpu_time_info hv_clock;
+ unsigned int time_offset;
+ struct page *time_page;
};
struct kvm_mem_alias {
@@ -287,6 +292,8 @@ struct kvm_arch{
int round_robin_prev_vcpu;
unsigned int tss_addr;
struct page *apic_access_page;
+
+ gpa_t wall_clock;
};
struct kvm_vm_stat {
diff --git a/include/asm-x86/kvm_para.h b/include/asm-x86/kvm_para.h
index c6f3fd8..5ab7d3d 100644
--- a/include/asm-x86/kvm_para.h
+++ b/include/asm-x86/kvm_para.h
@@ -10,10 +10,35 @@
* paravirtualization, the appropriate feature bit should be checked.
*/
#define KVM_CPUID_FEATURES 0x40000001
+#define KVM_FEATURE_CLOCKSOURCE 0
+
+#define MSR_KVM_WALL_CLOCK 0x11
+#define MSR_KVM_SYSTEM_TIME 0x12
#ifdef __KERNEL__
#include <asm/processor.h>
+/* xen binary-compatible interface. See xen headers for details */
+struct kvm_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 pad[3];
+} __attribute__((__packed__)); /* 32 bytes */
+
+struct kvm_wall_clock {
+ uint32_t wc_version;
+ uint32_t wc_sec;
+ uint32_t wc_nsec;
+} __attribute__((__packed__));
+
+
+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 c1ec04f..94540b3 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -233,6 +233,7 @@ struct kvm_vapic_addr {
#define KVM_CAP_SET_TSS_ADDR 4
#define KVM_CAP_VAPIC 6
#define KVM_CAP_EXT_CPUID 7
+#define KVM_CAP_CLOCKSOURCE 8
/*
* ioctls for VM fds
--
1.5.4.5
--
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