* [PATCH 2/2] kvmclock implementation, the guest part.
[not found] ` <12005010761561-git-send-email-gcosta-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
@ 2008-01-16 16:31 ` Glauber de Oliveira Costa
[not found] ` <1200501082989-git-send-email-gcosta-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2008-01-16 19:00 ` [PATCH 1/2] kvmclock - the host part Anthony Liguori
` (3 subsequent siblings)
4 siblings, 1 reply; 10+ messages in thread
From: Glauber de Oliveira Costa @ 2008-01-16 16:31 UTC (permalink / raw)
To: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f
Cc: jeremy-TSDbQ3PG+2Y, avi-atKUWr5tajBWk0Htik3J/w,
Glauber de Oliveira Costa
This is the guest part of kvm clock implementation
It does not do tsc-only timing, as tsc can have deltas
between cpus, and it did not seem worthy to me to keep
adjusting them.
We do use it, however, for fine-grained adjustment.
Other than that, time comes from the host.
Signed-off-by: Glauber de Oliveira Costa <gcosta-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
---
arch/x86/Kconfig | 10 +++
arch/x86/kernel/Makefile_32 | 1 +
arch/x86/kernel/kvmclock.c | 154 +++++++++++++++++++++++++++++++++++++++++++
arch/x86/kernel/setup_32.c | 5 ++
4 files changed, 170 insertions(+), 0 deletions(-)
create mode 100644 arch/x86/kernel/kvmclock.c
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index ab2df55..968315e 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -350,6 +350,16 @@ config VMI
at the moment), by linking the kernel to a GPL-ed ROM module
provided by the hypervisor.
+config KVM_CLOCK
+ bool "KVM paravirtualized clock"
+ select PARAVIRT
+ help
+ Turning on this option will allow you to run a paravirtualized clock
+ when running over the KVM hypervisor. Instead of relying on a PIT
+ (or probably other) emulation by the underlying device model, the host
+ provides the guest with timing infrastructure, as time of day, and
+ timer expiration.
+
source "arch/x86/lguest/Kconfig"
endif
diff --git a/arch/x86/kernel/Makefile_32 b/arch/x86/kernel/Makefile_32
index a7bc93c..f6332b6 100644
--- a/arch/x86/kernel/Makefile_32
+++ b/arch/x86/kernel/Makefile_32
@@ -44,6 +44,7 @@ obj-$(CONFIG_K8_NB) += k8.o
obj-$(CONFIG_MGEODE_LX) += geode_32.o mfgpt_32.o
obj-$(CONFIG_VMI) += vmi_32.o vmiclock_32.o
+obj-$(CONFIG_KVM_CLOCK) += kvmclock.o
obj-$(CONFIG_PARAVIRT) += paravirt_32.o
obj-y += pcspeaker.o
diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
new file mode 100644
index 0000000..56be828
--- /dev/null
+++ b/arch/x86/kernel/kvmclock.c
@@ -0,0 +1,154 @@
+/* KVM paravirtual clock driver. A clocksource implementation
+ Copyright (C) 2008 Glauber de Oliveira Costa, Red Hat Inc.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+*/
+
+#include <linux/clocksource.h>
+#include <linux/kvm_para.h>
+#include <asm/arch_hooks.h>
+#include <asm/msr.h>
+#include <xen/interface/xen.h>
+
+#define KVM_SCALE 22
+
+static int kvmclock = 1;
+
+static int parse_no_kvmclock(char *arg)
+{
+ kvmclock = 0;
+ return 0;
+}
+early_param("no-kvmclock", parse_no_kvmclock);
+
+struct shared_info shared_info __attribute__((__aligned__(PAGE_SIZE)));
+
+/* The hypervisor will put information about time periodically here */
+static struct kvm_vcpu_time_info hv_clock[NR_CPUS];
+#define get_clock(cpu, field) hv_clock[cpu].field
+
+static inline u64 kvm_get_delta(u64 last_tsc)
+{
+ int cpu = smp_processor_id();
+ u64 delta = native_read_tsc() - last_tsc;
+ return (delta * get_clock(cpu, tsc_to_system_mul)) >> KVM_SCALE;
+}
+
+static struct wall_clock wall_clock;
+/*
+ * The wallclock is the time of day when we booted. Since then, some time may
+ * have elapsed since the hypervisor wrote the data. So we try to account for
+ * that. Even if the tsc is not accurate, it gives us a more accurate timing
+ * than not adjusting at all
+ */
+unsigned long kvm_get_wallclock(void)
+{
+ u32 wc_sec, wc_nsec;
+ u64 delta, last_tsc;
+ struct timespec ts;
+ int version, nsec, cpu = smp_processor_id();
+
+ native_write_msr(MSR_KVM_WALL_CLOCK, __pa(&wall_clock));
+ do {
+ version = wall_clock.wc_version;
+ rmb();
+ wc_sec = wall_clock.wc_sec;
+ wc_nsec = wall_clock.wc_nsec;
+ last_tsc = get_clock(cpu, tsc_timestamp);
+ rmb();
+ } while ((wall_clock.wc_version != version) || (version & 1));
+
+ delta = kvm_get_delta(last_tsc);
+ delta += wc_nsec;
+ nsec = do_div(delta, NSEC_PER_SEC);
+ set_normalized_timespec(&ts, wc_sec + delta, nsec);
+ /*
+ * Of all mechanisms of time adjustment I've tested, this one
+ * was the champion!
+ */
+ return ts.tv_sec + 1;
+}
+
+int kvm_set_wallclock(unsigned long now)
+{
+ return 0;
+}
+
+/*
+ * This is our read_clock function. The host puts an tsc timestamp each time
+ * it updates a new time. Without the tsc adjustment, we can have a situation
+ * in which a vcpu starts to run earlier (smaller system_time), but probes
+ * time later (compared to another vcpu), leading to backwards time
+ */
+static cycle_t kvm_clock_read(void)
+{
+ u64 last_tsc, now;
+ int cpu;
+
+ preempt_disable();
+ cpu = smp_processor_id();
+
+ last_tsc = get_clock(cpu, tsc_timestamp);
+ now = get_clock(cpu, system_time);
+
+ now += kvm_get_delta(last_tsc);
+ preempt_enable();
+
+ return now;
+}
+
+static struct clocksource kvm_clock = {
+ .name = "kvm-clock",
+ .read = kvm_clock_read,
+ .rating = 400,
+ .mask = CLOCKSOURCE_MASK(64),
+ .mult = 1 << KVM_SCALE,
+ .shift = KVM_SCALE,
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static int kvm_register_clock(void)
+{
+ int cpu = smp_processor_id();
+
+ return native_write_msr_safe(MSR_KVM_SYSTEM_TIME, __pa(&hv_clock[cpu]));
+}
+
+static void kvm_setup_secondary_clock(void)
+{
+ /*
+ * Now that the first cpu already had this clocksource initialized,
+ * we shouldn't fail.
+ */
+ WARN_ON(kvm_register_clock());
+ /* ok, done with our trickery, call native */
+ setup_secondary_APIC_clock();
+}
+
+void __init kvmclock_init(void)
+{
+ if (!kvm_para_available())
+ return;
+
+ if (kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE)) {
+ if (kvm_register_clock())
+ return;
+ pv_time_ops.get_wallclock = kvm_get_wallclock;
+ pv_time_ops.set_wallclock = kvm_set_wallclock;
+ pv_time_ops.sched_clock = kvm_clock_read;
+ pv_apic_ops.setup_secondary_clock = kvm_setup_secondary_clock;
+ clocksource_register(&kvm_clock);
+ }
+}
diff --git a/arch/x86/kernel/setup_32.c b/arch/x86/kernel/setup_32.c
index 9c24b45..89c0eb2 100644
--- a/arch/x86/kernel/setup_32.c
+++ b/arch/x86/kernel/setup_32.c
@@ -44,6 +44,7 @@
#include <linux/crash_dump.h>
#include <linux/dmi.h>
#include <linux/pfn.h>
+#include <linux/kvm_para.h>
#include <video/edid.h>
@@ -614,6 +615,10 @@ void __init setup_arch(char **cmdline_p)
max_low_pfn = setup_memory();
+#ifdef CONFIG_KVM_CLOCK
+ kvmclock_init();
+#endif
+
#ifdef CONFIG_VMI
/*
* Must be after max_low_pfn is determined, and before kernel
--
1.5.0.6
-------------------------------------------------------------------------
This SF.net email is sponsored by: Microsoft
Defy all challenges. Microsoft(R) Visual Studio 2008.
http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
^ permalink raw reply related [flat|nested] 10+ messages in thread* Re: [PATCH 1/2] kvmclock - the host part.
[not found] ` <12005010761561-git-send-email-gcosta-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2008-01-16 16:31 ` [PATCH 2/2] kvmclock implementation, the guest part Glauber de Oliveira Costa
@ 2008-01-16 19:00 ` Anthony Liguori
[not found] ` <478E544C.4020603-rdkfGonbjUSkNkDKm+mE6A@public.gmane.org>
2008-01-17 7:59 ` Gerd Hoffmann
` (2 subsequent siblings)
4 siblings, 1 reply; 10+ messages in thread
From: Anthony Liguori @ 2008-01-16 19:00 UTC (permalink / raw)
To: Glauber de Oliveira Costa
Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f, jeremy-TSDbQ3PG+2Y,
avi-atKUWr5tajBWk0Htik3J/w
Glauber de Oliveira Costa wrote:
> 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 <gcosta-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> ---
> arch/x86/kvm/x86.c | 98 +++++++++++++++++++++++++++++++++++++++++++-
> include/asm-x86/kvm_host.h | 6 +++
> include/asm-x86/kvm_para.h | 24 +++++++++++
> include/linux/kvm.h | 1 +
> 4 files changed, 128 insertions(+), 1 deletions(-)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 8a90403..fd69aa1 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_SYSTEM_TIME,
> };
>
> static unsigned num_msrs_to_save;
> @@ -467,6 +468,73 @@ 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_vcpu *v, gpa_t wall_clock)
> +{
> + int version = 1;
> + struct wall_clock wc;
> + unsigned long flags;
> + struct timespec wc_ts;
> +
> + local_irq_save(flags);
> + kvm_get_msr(v, MSR_IA32_TIME_STAMP_COUNTER,
> + &v->arch.hv_clock.tsc_timestamp);
> + wc_ts = current_kernel_time();
> + local_irq_restore(flags);
> +
> + down_write(¤t->mm->mmap_sem);
> + kvm_write_guest(v->kvm, wall_clock, &version, sizeof(version));
> + up_write(¤t->mm->mmap_sem);
> +
> + /* With all the info we got, fill in the values */
> + wc.wc_sec = wc_ts.tv_sec;
> + wc.wc_nsec = wc_ts.tv_nsec;
> + wc.wc_version = ++version;
> +
> + down_write(¤t->mm->mmap_sem);
> + kvm_write_guest(v->kvm, wall_clock, &wc, sizeof(wc));
> + up_write(¤t->mm->mmap_sem);
>
Can we get a comment explaining why we only write the version field and
then immediately increment the version and write the whole struct? It's
not at all obvious why the first write is needed to me.
> +}
> +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 states,
> + * we just write "2" at the end
> + */
> + vcpu->hv_clock.version = 2;
> +
> + preempt_disable();
> +
> + 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);
>
Instead of doing a kmap/memcpy, I think it would be better to store the
GPA of the time page and do a kvm_write_guest(). Otherwise, you're
pinning this page in memory.
Regards,
Anthony Liguori
> + preempt_enable();
> +
> + mark_page_dirty(v->kvm, vcpu->time >> PAGE_SHIFT);
> +}
> +
>
> int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
> {
> @@ -494,6 +562,25 @@ 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->arch.wall_clock = data;
> + kvm_write_wall_clock(vcpu, data);
> + break;
> + case MSR_KVM_SYSTEM_TIME: {
> + vcpu->arch.time = data & PAGE_MASK;
> + vcpu->arch.time_offset = data & ~PAGE_MASK;
> +
> + 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.time_page = gfn_to_page(vcpu->kvm, data >> PAGE_SHIFT);
> + up_write(¤t->mm->mmap_sem);
> + if (is_error_page(vcpu->arch.time_page))
> + vcpu->arch.time_page = NULL;
> + break;
> + }
> default:
> pr_unimpl(vcpu, "unhandled wrmsr: 0x%x data %llx\n", msr, data);
> return 1;
> @@ -553,6 +640,13 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
> data = vcpu->arch.shadow_efer;
> break;
> #endif
> + case MSR_KVM_WALL_CLOCK:
> + data = vcpu->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;
> @@ -680,6 +774,7 @@ 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 +832,7 @@ 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..2a621ee 100644
> --- a/include/asm-x86/kvm_host.h
> +++ b/include/asm-x86/kvm_host.h
> @@ -261,6 +261,12 @@ struct kvm_vcpu_arch {
> /* emulate context */
>
> struct x86_emulate_ctxt emulate_ctxt;
> +
> + gpa_t wall_clock;
> + gpa_t time;
> + struct kvm_vcpu_time_info hv_clock;
> + unsigned int time_offset;
> + struct page *time_page;
> };
>
> struct kvm_mem_alias {
> diff --git a/include/asm-x86/kvm_para.h b/include/asm-x86/kvm_para.h
> index c6f3fd8..8c105bc 100644
> --- a/include/asm-x86/kvm_para.h
> +++ b/include/asm-x86/kvm_para.h
> @@ -10,10 +10,34 @@
> * 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;
> +}; /* 32 bytes */
> +
> +struct wall_clock {
> + uint32_t wc_version;
> + uint32_t wc_sec;
> + uint32_t wc_nsec;
> +};
> +
> +
> +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
>
-------------------------------------------------------------------------
This SF.net email is sponsored by: Microsoft
Defy all challenges. Microsoft(R) Visual Studio 2008.
http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
^ permalink raw reply [flat|nested] 10+ messages in thread* Re: [PATCH 1/2] kvmclock - the host part.
[not found] ` <12005010761561-git-send-email-gcosta-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2008-01-16 16:31 ` [PATCH 2/2] kvmclock implementation, the guest part Glauber de Oliveira Costa
2008-01-16 19:00 ` [PATCH 1/2] kvmclock - the host part Anthony Liguori
@ 2008-01-17 7:59 ` Gerd Hoffmann
2008-01-20 15:37 ` Avi Kivity
2008-01-20 15:38 ` Avi Kivity
4 siblings, 0 replies; 10+ messages in thread
From: Gerd Hoffmann @ 2008-01-17 7:59 UTC (permalink / raw)
To: Glauber de Oliveira Costa
Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f, jeremy-TSDbQ3PG+2Y,
avi-atKUWr5tajBWk0Htik3J/w
Glauber de Oliveira Costa wrote:
> 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.
comment needs an update too ;)
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> - MSR_IA32_TIME_STAMP_COUNTER,
> + MSR_IA32_TIME_STAMP_COUNTER, MSR_KVM_SYSTEM_TIME,
+ MSR_KVM_WALL_CLOCK
Looks good otherwise.
cheers,
Gerd
-------------------------------------------------------------------------
This SF.net email is sponsored by: Microsoft
Defy all challenges. Microsoft(R) Visual Studio 2008.
http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
^ permalink raw reply [flat|nested] 10+ messages in thread* Re: [PATCH 1/2] kvmclock - the host part.
[not found] ` <12005010761561-git-send-email-gcosta-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
` (2 preceding siblings ...)
2008-01-17 7:59 ` Gerd Hoffmann
@ 2008-01-20 15:37 ` Avi Kivity
2008-01-20 15:38 ` Avi Kivity
4 siblings, 0 replies; 10+ messages in thread
From: Avi Kivity @ 2008-01-20 15:37 UTC (permalink / raw)
To: Glauber de Oliveira Costa
Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f, jeremy-TSDbQ3PG+2Y
Glauber de Oliveira Costa wrote:
> 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 <gcosta-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> ---
> arch/x86/kvm/x86.c | 98 +++++++++++++++++++++++++++++++++++++++++++-
> include/asm-x86/kvm_host.h | 6 +++
> include/asm-x86/kvm_para.h | 24 +++++++++++
> include/linux/kvm.h | 1 +
> 4 files changed, 128 insertions(+), 1 deletions(-)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 8a90403..fd69aa1 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_SYSTEM_TIME,
>
Missing second MSR here.
>
> +static void kvm_write_wall_clock(struct kvm_vcpu *v, gpa_t wall_clock)
> +{
> + int version = 1;
> + struct wall_clock wc;
> + unsigned long flags;
> + struct timespec wc_ts;
> +
> + local_irq_save(flags);
> + kvm_get_msr(v, MSR_IA32_TIME_STAMP_COUNTER,
> + &v->arch.hv_clock.tsc_timestamp);
> + wc_ts = current_kernel_time();
> + local_irq_restore(flags);
> +
> + down_write(¤t->mm->mmap_sem);
> + kvm_write_guest(v->kvm, wall_clock, &version, sizeof(version));
> + up_write(¤t->mm->mmap_sem);
> +
> + /* With all the info we got, fill in the values */
> + wc.wc_sec = wc_ts.tv_sec;
> + wc.wc_nsec = wc_ts.tv_nsec;
> + wc.wc_version = ++version;
> +
> + down_write(¤t->mm->mmap_sem);
> + kvm_write_guest(v->kvm, wall_clock, &wc, sizeof(wc));
> + up_write(¤t->mm->mmap_sem);
> +}
>
missing blank line
> +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 states,
> + * we just write "2" at the end
> + */
> + vcpu->hv_clock.version = 2;
> +
> + preempt_disable();
>
vcpu_load() is not preemptible anyway (and cannot be).
> +
> + 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);
> + preempt_enable();
> +
> + mark_page_dirty(v->kvm, vcpu->time >> PAGE_SHIFT);
> +}
> +
>
> int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
> {
> @@ -494,6 +562,25 @@ 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->arch.wall_clock = data;
>
This better be a global msr (in kvm->, not vcpu->). There is precedent;
some msrs in hyperthreading-capable processors are global to a core.
We need some notification to update wall clock as a result of
time-of-day step changes, due to ntp or the user setting the date.
Hopefully such a notifier exists.
--
error compiling committee.c: too many arguments to function
-------------------------------------------------------------------------
This SF.net email is sponsored by: Microsoft
Defy all challenges. Microsoft(R) Visual Studio 2008.
http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
^ permalink raw reply [flat|nested] 10+ messages in thread* Re: [PATCH 1/2] kvmclock - the host part.
[not found] ` <12005010761561-git-send-email-gcosta-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
` (3 preceding siblings ...)
2008-01-20 15:37 ` Avi Kivity
@ 2008-01-20 15:38 ` Avi Kivity
4 siblings, 0 replies; 10+ messages in thread
From: Avi Kivity @ 2008-01-20 15:38 UTC (permalink / raw)
To: Glauber de Oliveira Costa
Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f, jeremy-TSDbQ3PG+2Y
Glauber de Oliveira Costa wrote:
> +
> +struct wall_clock {
> + uint32_t wc_version;
> + uint32_t wc_sec;
> + uint32_t wc_nsec;
> +};
> +
>
kvm_wall_clock?
--
error compiling committee.c: too many arguments to function
-------------------------------------------------------------------------
This SF.net email is sponsored by: Microsoft
Defy all challenges. Microsoft(R) Visual Studio 2008.
http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
^ permalink raw reply [flat|nested] 10+ messages in thread