diff options
| author | Marcelo Tosatti <mtosatti@redhat.com> | 2014-01-06 12:00:02 -0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-02-06 11:08:12 -0800 |
| commit | 512f3430cf8aa7047245d94904af8df210bf4ecd (patch) | |
| tree | 511244fd36dd88ed6d401653bfe2a2815d82bb3a | |
| parent | 5a45f3d11a80155ef9997cb1389a9213f9801f7f (diff) | |
| download | lwn-512f3430cf8aa7047245d94904af8df210bf4ecd.tar.gz lwn-512f3430cf8aa7047245d94904af8df210bf4ecd.zip | |
KVM: x86: limit PIT timer frequency
commit 9ed96e87c5748de4c2807ef17e81287c7304186c upstream.
Limit PIT timer frequency similarly to the limit applied by
LAPIC timer.
Reviewed-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/x86/kvm/i8254.c | 18 | ||||
| -rw-r--r-- | arch/x86/kvm/lapic.c | 3 | ||||
| -rw-r--r-- | arch/x86/kvm/x86.c | 3 | ||||
| -rw-r--r-- | arch/x86/kvm/x86.h | 2 |
4 files changed, 23 insertions, 3 deletions
diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c index 412a5aa0ef94..518d86471b76 100644 --- a/arch/x86/kvm/i8254.c +++ b/arch/x86/kvm/i8254.c @@ -37,6 +37,7 @@ #include "irq.h" #include "i8254.h" +#include "x86.h" #ifndef CONFIG_X86_64 #define mod_64(x, y) ((x) - (y) * div64_u64(x, y)) @@ -349,6 +350,23 @@ static void create_pit_timer(struct kvm *kvm, u32 val, int is_period) atomic_set(&ps->pending, 0); ps->irq_ack = 1; + /* + * Do not allow the guest to program periodic timers with small + * interval, since the hrtimers are not throttled by the host + * scheduler. + */ + if (ps->is_periodic) { + s64 min_period = min_timer_period_us * 1000LL; + + if (ps->period < min_period) { + pr_info_ratelimited( + "kvm: requested %lld ns " + "i8254 timer period limited to %lld ns\n", + ps->period, min_period); + ps->period = min_period; + } + } + hrtimer_start(&ps->timer, ktime_add_ns(ktime_get(), interval), HRTIMER_MODE_ABS); } diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 683bf5057e7a..61d9fed5eb31 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -71,9 +71,6 @@ #define VEC_POS(v) ((v) & (32 - 1)) #define REG_POS(v) (((v) >> 5) << 4) -static unsigned int min_timer_period_us = 500; -module_param(min_timer_period_us, uint, S_IRUGO | S_IWUSR); - static inline void apic_set_reg(struct kvm_lapic *apic, int reg_off, u32 val) { *((u32 *) (apic->regs + reg_off)) = val; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index ad6a01605aaa..1bd6ea07d7d3 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -94,6 +94,9 @@ EXPORT_SYMBOL_GPL(kvm_x86_ops); static bool ignore_msrs = 0; module_param(ignore_msrs, bool, S_IRUGO | S_IWUSR); +unsigned int min_timer_period_us = 500; +module_param(min_timer_period_us, uint, S_IRUGO | S_IWUSR); + bool kvm_has_tsc_control; EXPORT_SYMBOL_GPL(kvm_has_tsc_control); u32 kvm_max_guest_tsc_khz; diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h index e224f7a671b6..3186542f2fa3 100644 --- a/arch/x86/kvm/x86.h +++ b/arch/x86/kvm/x86.h @@ -124,5 +124,7 @@ int kvm_write_guest_virt_system(struct x86_emulate_ctxt *ctxt, extern u64 host_xcr0; +extern unsigned int min_timer_period_us; + extern struct static_key kvm_no_apic_vcpu; #endif |