diff options
author | Glauber de Oliveira Costa <gcosta@redhat.com> | 2008-02-15 14:52:48 -0500 |
---|---|---|
committer | Avi Kivity <avi@qumranet.com> | 2008-04-27 04:53:22 -0400 |
commit | 790c73f6289a204f858ffdcbe4a2b38e91657ec6 (patch) | |
tree | 3d6b146538b11e45a713bb4fa1b44af4509ca27f /arch/x86 | |
parent | 18068523d3a0b41fcee5b53cdb437a0ab4d65e4b (diff) |
x86: KVM guest: paravirtualized clocksource
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.
[randy dunlap: add missing include]
[randy dunlap: disallow on Voyager or Visual WS]
Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
Diffstat (limited to 'arch/x86')
-rw-r--r-- | arch/x86/Kconfig | 11 | ||||
-rw-r--r-- | arch/x86/kernel/Makefile | 1 | ||||
-rw-r--r-- | arch/x86/kernel/kvmclock.c | 160 | ||||
-rw-r--r-- | arch/x86/kernel/setup_32.c | 5 | ||||
-rw-r--r-- | arch/x86/kernel/setup_64.c | 5 |
5 files changed, 182 insertions, 0 deletions
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 2fadf794483d..40cedc255eda 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig | |||
@@ -373,6 +373,17 @@ config VMI | |||
373 | at the moment), by linking the kernel to a GPL-ed ROM module | 373 | at the moment), by linking the kernel to a GPL-ed ROM module |
374 | provided by the hypervisor. | 374 | provided by the hypervisor. |
375 | 375 | ||
376 | config KVM_CLOCK | ||
377 | bool "KVM paravirtualized clock" | ||
378 | select PARAVIRT | ||
379 | depends on !(X86_VISWS || X86_VOYAGER) | ||
380 | help | ||
381 | Turning on this option will allow you to run a paravirtualized clock | ||
382 | when running over the KVM hypervisor. Instead of relying on a PIT | ||
383 | (or probably other) emulation by the underlying device model, the host | ||
384 | provides the guest with timing infrastructure such as time of day, and | ||
385 | system time | ||
386 | |||
376 | source "arch/x86/lguest/Kconfig" | 387 | source "arch/x86/lguest/Kconfig" |
377 | 388 | ||
378 | config PARAVIRT | 389 | config PARAVIRT |
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index 90e092d0af0c..483047a33024 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile | |||
@@ -80,6 +80,7 @@ obj-$(CONFIG_DEBUG_RODATA_TEST) += test_rodata.o | |||
80 | obj-$(CONFIG_DEBUG_NX_TEST) += test_nx.o | 80 | obj-$(CONFIG_DEBUG_NX_TEST) += test_nx.o |
81 | 81 | ||
82 | obj-$(CONFIG_VMI) += vmi_32.o vmiclock_32.o | 82 | obj-$(CONFIG_VMI) += vmi_32.o vmiclock_32.o |
83 | obj-$(CONFIG_KVM_CLOCK) += kvmclock.o | ||
83 | obj-$(CONFIG_PARAVIRT) += paravirt.o paravirt_patch_$(BITS).o | 84 | obj-$(CONFIG_PARAVIRT) += paravirt.o paravirt_patch_$(BITS).o |
84 | 85 | ||
85 | ifdef CONFIG_INPUT_PCSPKR | 86 | ifdef CONFIG_INPUT_PCSPKR |
diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c new file mode 100644 index 000000000000..b999f5e5b3bf --- /dev/null +++ b/arch/x86/kernel/kvmclock.c | |||
@@ -0,0 +1,160 @@ | |||
1 | /* KVM paravirtual clock driver. A clocksource implementation | ||
2 | Copyright (C) 2008 Glauber de Oliveira Costa, Red Hat Inc. | ||
3 | |||
4 | This program is free software; you can redistribute it and/or modify | ||
5 | it under the terms of the GNU General Public License as published by | ||
6 | the Free Software Foundation; either version 2 of the License, or | ||
7 | (at your option) any later version. | ||
8 | |||
9 | This program is distributed in the hope that it will be useful, | ||
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
12 | GNU General Public License for more details. | ||
13 | |||
14 | You should have received a copy of the GNU General Public License | ||
15 | along with this program; if not, write to the Free Software | ||
16 | Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA | ||
17 | */ | ||
18 | |||
19 | #include <linux/clocksource.h> | ||
20 | #include <linux/kvm_para.h> | ||
21 | #include <asm/arch_hooks.h> | ||
22 | #include <asm/msr.h> | ||
23 | #include <asm/apic.h> | ||
24 | #include <linux/percpu.h> | ||
25 | |||
26 | #define KVM_SCALE 22 | ||
27 | |||
28 | static int kvmclock = 1; | ||
29 | |||
30 | static int parse_no_kvmclock(char *arg) | ||
31 | { | ||
32 | kvmclock = 0; | ||
33 | return 0; | ||
34 | } | ||
35 | early_param("no-kvmclock", parse_no_kvmclock); | ||
36 | |||
37 | /* The hypervisor will put information about time periodically here */ | ||
38 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct kvm_vcpu_time_info, hv_clock); | ||
39 | #define get_clock(cpu, field) per_cpu(hv_clock, cpu).field | ||
40 | |||
41 | static inline u64 kvm_get_delta(u64 last_tsc) | ||
42 | { | ||
43 | int cpu = smp_processor_id(); | ||
44 | u64 delta = native_read_tsc() - last_tsc; | ||
45 | return (delta * get_clock(cpu, tsc_to_system_mul)) >> KVM_SCALE; | ||
46 | } | ||
47 | |||
48 | static struct kvm_wall_clock wall_clock; | ||
49 | static cycle_t kvm_clock_read(void); | ||
50 | /* | ||
51 | * The wallclock is the time of day when we booted. Since then, some time may | ||
52 | * have elapsed since the hypervisor wrote the data. So we try to account for | ||
53 | * that with system time | ||
54 | */ | ||
55 | unsigned long kvm_get_wallclock(void) | ||
56 | { | ||
57 | u32 wc_sec, wc_nsec; | ||
58 | u64 delta; | ||
59 | struct timespec ts; | ||
60 | int version, nsec; | ||
61 | int low, high; | ||
62 | |||
63 | low = (int)__pa(&wall_clock); | ||
64 | high = ((u64)__pa(&wall_clock) >> 32); | ||
65 | |||
66 | delta = kvm_clock_read(); | ||
67 | |||
68 | native_write_msr(MSR_KVM_WALL_CLOCK, low, high); | ||
69 | do { | ||
70 | version = wall_clock.wc_version; | ||
71 | rmb(); | ||
72 | wc_sec = wall_clock.wc_sec; | ||
73 | wc_nsec = wall_clock.wc_nsec; | ||
74 | rmb(); | ||
75 | } while ((wall_clock.wc_version != version) || (version & 1)); | ||
76 | |||
77 | delta = kvm_clock_read() - delta; | ||
78 | delta += wc_nsec; | ||
79 | nsec = do_div(delta, NSEC_PER_SEC); | ||
80 | set_normalized_timespec(&ts, wc_sec + delta, nsec); | ||
81 | /* | ||
82 | * Of all mechanisms of time adjustment I've tested, this one | ||
83 | * was the champion! | ||
84 | */ | ||
85 | return ts.tv_sec + 1; | ||
86 | } | ||
87 | |||
88 | int kvm_set_wallclock(unsigned long now) | ||
89 | { | ||
90 | return 0; | ||
91 | } | ||
92 | |||
93 | /* | ||
94 | * This is our read_clock function. The host puts an tsc timestamp each time | ||
95 | * it updates a new time. Without the tsc adjustment, we can have a situation | ||
96 | * in which a vcpu starts to run earlier (smaller system_time), but probes | ||
97 | * time later (compared to another vcpu), leading to backwards time | ||
98 | */ | ||
99 | static cycle_t kvm_clock_read(void) | ||
100 | { | ||
101 | u64 last_tsc, now; | ||
102 | int cpu; | ||
103 | |||
104 | preempt_disable(); | ||
105 | cpu = smp_processor_id(); | ||
106 | |||
107 | last_tsc = get_clock(cpu, tsc_timestamp); | ||
108 | now = get_clock(cpu, system_time); | ||
109 | |||
110 | now += kvm_get_delta(last_tsc); | ||
111 | preempt_enable(); | ||
112 | |||
113 | return now; | ||
114 | } | ||
115 | static struct clocksource kvm_clock = { | ||
116 | .name = "kvm-clock", | ||
117 | .read = kvm_clock_read, | ||
118 | .rating = 400, | ||
119 | .mask = CLOCKSOURCE_MASK(64), | ||
120 | .mult = 1 << KVM_SCALE, | ||
121 | .shift = KVM_SCALE, | ||
122 | .flags = CLOCK_SOURCE_IS_CONTINUOUS, | ||
123 | }; | ||
124 | |||
125 | static int kvm_register_clock(void) | ||
126 | { | ||
127 | int cpu = smp_processor_id(); | ||
128 | int low, high; | ||
129 | low = (int)__pa(&per_cpu(hv_clock, cpu)) | 1; | ||
130 | high = ((u64)__pa(&per_cpu(hv_clock, cpu)) >> 32); | ||
131 | |||
132 | return native_write_msr_safe(MSR_KVM_SYSTEM_TIME, low, high); | ||
133 | } | ||
134 | |||
135 | static void kvm_setup_secondary_clock(void) | ||
136 | { | ||
137 | /* | ||
138 | * Now that the first cpu already had this clocksource initialized, | ||
139 | * we shouldn't fail. | ||
140 | */ | ||
141 | WARN_ON(kvm_register_clock()); | ||
142 | /* ok, done with our trickery, call native */ | ||
143 | setup_secondary_APIC_clock(); | ||
144 | } | ||
145 | |||
146 | void __init kvmclock_init(void) | ||
147 | { | ||
148 | if (!kvm_para_available()) | ||
149 | return; | ||
150 | |||
151 | if (kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE)) { | ||
152 | if (kvm_register_clock()) | ||
153 | return; | ||
154 | pv_time_ops.get_wallclock = kvm_get_wallclock; | ||
155 | pv_time_ops.set_wallclock = kvm_set_wallclock; | ||
156 | pv_time_ops.sched_clock = kvm_clock_read; | ||
157 | pv_apic_ops.setup_secondary_clock = kvm_setup_secondary_clock; | ||
158 | clocksource_register(&kvm_clock); | ||
159 | } | ||
160 | } | ||
diff --git a/arch/x86/kernel/setup_32.c b/arch/x86/kernel/setup_32.c index 44cc9b933932..5a849ddd09ee 100644 --- a/arch/x86/kernel/setup_32.c +++ b/arch/x86/kernel/setup_32.c | |||
@@ -47,6 +47,7 @@ | |||
47 | #include <linux/pfn.h> | 47 | #include <linux/pfn.h> |
48 | #include <linux/pci.h> | 48 | #include <linux/pci.h> |
49 | #include <linux/init_ohci1394_dma.h> | 49 | #include <linux/init_ohci1394_dma.h> |
50 | #include <linux/kvm_para.h> | ||
50 | 51 | ||
51 | #include <video/edid.h> | 52 | #include <video/edid.h> |
52 | 53 | ||
@@ -820,6 +821,10 @@ void __init setup_arch(char **cmdline_p) | |||
820 | 821 | ||
821 | max_low_pfn = setup_memory(); | 822 | max_low_pfn = setup_memory(); |
822 | 823 | ||
824 | #ifdef CONFIG_KVM_CLOCK | ||
825 | kvmclock_init(); | ||
826 | #endif | ||
827 | |||
823 | #ifdef CONFIG_VMI | 828 | #ifdef CONFIG_VMI |
824 | /* | 829 | /* |
825 | * Must be after max_low_pfn is determined, and before kernel | 830 | * Must be after max_low_pfn is determined, and before kernel |
diff --git a/arch/x86/kernel/setup_64.c b/arch/x86/kernel/setup_64.c index 60e64c8eee92..8a9213c023ef 100644 --- a/arch/x86/kernel/setup_64.c +++ b/arch/x86/kernel/setup_64.c | |||
@@ -42,6 +42,7 @@ | |||
42 | #include <linux/ctype.h> | 42 | #include <linux/ctype.h> |
43 | #include <linux/uaccess.h> | 43 | #include <linux/uaccess.h> |
44 | #include <linux/init_ohci1394_dma.h> | 44 | #include <linux/init_ohci1394_dma.h> |
45 | #include <linux/kvm_para.h> | ||
45 | 46 | ||
46 | #include <asm/mtrr.h> | 47 | #include <asm/mtrr.h> |
47 | #include <asm/uaccess.h> | 48 | #include <asm/uaccess.h> |
@@ -384,6 +385,10 @@ void __init setup_arch(char **cmdline_p) | |||
384 | 385 | ||
385 | io_delay_init(); | 386 | io_delay_init(); |
386 | 387 | ||
388 | #ifdef CONFIG_KVM_CLOCK | ||
389 | kvmclock_init(); | ||
390 | #endif | ||
391 | |||
387 | #ifdef CONFIG_SMP | 392 | #ifdef CONFIG_SMP |
388 | /* setup to use the early static init tables during kernel startup */ | 393 | /* setup to use the early static init tables during kernel startup */ |
389 | x86_cpu_to_apicid_early_ptr = (void *)x86_cpu_to_apicid_init; | 394 | x86_cpu_to_apicid_early_ptr = (void *)x86_cpu_to_apicid_init; |