x86: kvmclock: allocate pvclock shared memory area
We want to expose the pvclock shared memory areas, which
the hypervisor periodically updates, to userspace.
For a linear mapping from userspace, it is necessary that
entire page sized regions are used for array of pvclock
structures.
There is no such guarantee with per cpu areas, therefore move
to memblock_alloc based allocation.
Acked-by: Glauber Costa <glommer@parallels.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
index f1b42b3..c7d7567 100644
--- a/arch/x86/kernel/kvmclock.c
+++ b/arch/x86/kernel/kvmclock.c
@@ -23,6 +23,7 @@
#include <asm/apic.h>
#include <linux/percpu.h>
#include <linux/hardirq.h>
+#include <linux/memblock.h>
#include <asm/x86_init.h>
#include <asm/reboot.h>
@@ -39,7 +40,11 @@
early_param("no-kvmclock", parse_no_kvmclock);
/* The hypervisor will put information about time periodically here */
-static DEFINE_PER_CPU_SHARED_ALIGNED(struct pvclock_vcpu_time_info, hv_clock);
+struct pvclock_aligned_vcpu_time_info {
+ struct pvclock_vcpu_time_info clock;
+} __attribute__((__aligned__(SMP_CACHE_BYTES)));
+
+static struct pvclock_aligned_vcpu_time_info *hv_clock;
static struct pvclock_wall_clock wall_clock;
/*
@@ -52,15 +57,20 @@
struct pvclock_vcpu_time_info *vcpu_time;
struct timespec ts;
int low, high;
+ int cpu;
low = (int)__pa_symbol(&wall_clock);
high = ((u64)__pa_symbol(&wall_clock) >> 32);
native_write_msr(msr_kvm_wall_clock, low, high);
- vcpu_time = &get_cpu_var(hv_clock);
+ preempt_disable();
+ cpu = smp_processor_id();
+
+ vcpu_time = &hv_clock[cpu].clock;
pvclock_read_wallclock(&wall_clock, vcpu_time, &ts);
- put_cpu_var(hv_clock);
+
+ preempt_enable();
return ts.tv_sec;
}
@@ -74,9 +84,11 @@
{
struct pvclock_vcpu_time_info *src;
cycle_t ret;
+ int cpu;
preempt_disable_notrace();
- src = &__get_cpu_var(hv_clock);
+ cpu = smp_processor_id();
+ src = &hv_clock[cpu].clock;
ret = pvclock_clocksource_read(src);
preempt_enable_notrace();
return ret;
@@ -99,8 +111,15 @@
static unsigned long kvm_get_tsc_khz(void)
{
struct pvclock_vcpu_time_info *src;
- src = &per_cpu(hv_clock, 0);
- return pvclock_tsc_khz(src);
+ int cpu;
+ unsigned long tsc_khz;
+
+ preempt_disable();
+ cpu = smp_processor_id();
+ src = &hv_clock[cpu].clock;
+ tsc_khz = pvclock_tsc_khz(src);
+ preempt_enable();
+ return tsc_khz;
}
static void kvm_get_preset_lpj(void)
@@ -119,10 +138,14 @@
{
bool ret = false;
struct pvclock_vcpu_time_info *src;
+ int cpu = smp_processor_id();
- src = &__get_cpu_var(hv_clock);
+ if (!hv_clock)
+ return ret;
+
+ src = &hv_clock[cpu].clock;
if ((src->flags & PVCLOCK_GUEST_STOPPED) != 0) {
- __this_cpu_and(hv_clock.flags, ~PVCLOCK_GUEST_STOPPED);
+ src->flags &= ~PVCLOCK_GUEST_STOPPED;
ret = true;
}
@@ -141,9 +164,10 @@
{
int cpu = smp_processor_id();
int low, high, ret;
+ struct pvclock_vcpu_time_info *src = &hv_clock[cpu].clock;
- low = (int)__pa(&per_cpu(hv_clock, cpu)) | 1;
- high = ((u64)__pa(&per_cpu(hv_clock, cpu)) >> 32);
+ low = (int)__pa(src) | 1;
+ high = ((u64)__pa(src) >> 32);
ret = native_write_msr_safe(msr_kvm_system_time, low, high);
printk(KERN_INFO "kvm-clock: cpu %d, msr %x:%x, %s\n",
cpu, high, low, txt);
@@ -197,6 +221,8 @@
void __init kvmclock_init(void)
{
+ unsigned long mem;
+
if (!kvm_para_available())
return;
@@ -209,8 +235,18 @@
printk(KERN_INFO "kvm-clock: Using msrs %x and %x",
msr_kvm_system_time, msr_kvm_wall_clock);
- if (kvm_register_clock("boot clock"))
+ mem = memblock_alloc(sizeof(struct pvclock_aligned_vcpu_time_info) * NR_CPUS,
+ PAGE_SIZE);
+ if (!mem)
return;
+ hv_clock = __va(mem);
+
+ if (kvm_register_clock("boot clock")) {
+ hv_clock = NULL;
+ memblock_free(mem,
+ sizeof(struct pvclock_aligned_vcpu_time_info)*NR_CPUS);
+ return;
+ }
pv_time_ops.sched_clock = kvm_clock_read;
x86_platform.calibrate_tsc = kvm_get_tsc_khz;
x86_platform.get_wallclock = kvm_get_wallclock;