From 15ad71460d75fd7ca41bb248a2310f3f39b302ba Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Wed, 11 Jul 2007 18:17:21 +0300 Subject: KVM: Use the scheduler preemption notifiers to make kvm preemptible Current kvm disables preemption while the new virtualization registers are in use. This of course is not very good for latency sensitive workloads (one use of virtualization is to offload user interface and other latency insensitive stuff to a container, so that it is easier to analyze the remaining workload). This patch re-enables preemption for kvm; preemption is now only disabled when switching the registers in and out, and during the switch to guest mode and back. Contains fixes from Shaohua Li . Signed-off-by: Avi Kivity --- drivers/kvm/vmx.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-) (limited to 'drivers/kvm/vmx.c') diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c index 18f9b0b3fb1..8c87d20f8e3 100644 --- a/drivers/kvm/vmx.c +++ b/drivers/kvm/vmx.c @@ -396,6 +396,7 @@ static void vmx_save_host_state(struct kvm_vcpu *vcpu) static void vmx_load_host_state(struct kvm_vcpu *vcpu) { struct vcpu_vmx *vmx = to_vmx(vcpu); + unsigned long flags; if (!vmx->host_state.loaded) return; @@ -408,12 +409,12 @@ static void vmx_load_host_state(struct kvm_vcpu *vcpu) * If we have to reload gs, we must take care to * preserve our gs base. */ - local_irq_disable(); + local_irq_save(flags); load_gs(vmx->host_state.gs_sel); #ifdef CONFIG_X86_64 wrmsrl(MSR_GS_BASE, vmcs_readl(HOST_GS_BASE)); #endif - local_irq_enable(); + local_irq_restore(flags); reload_tss(); } @@ -427,15 +428,12 @@ static void vmx_load_host_state(struct kvm_vcpu *vcpu) * Switches to specified vcpu, until a matching vcpu_put(), but assumes * vcpu mutex is already taken. */ -static void vmx_vcpu_load(struct kvm_vcpu *vcpu) +static void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu) { struct vcpu_vmx *vmx = to_vmx(vcpu); u64 phys_addr = __pa(vmx->vmcs); - int cpu; u64 tsc_this, delta; - cpu = get_cpu(); - if (vcpu->cpu != cpu) vcpu_clear(vcpu); @@ -480,7 +478,6 @@ static void vmx_vcpu_put(struct kvm_vcpu *vcpu) { vmx_load_host_state(vcpu); kvm_put_guest_fpu(vcpu); - put_cpu(); } static void vmx_fpu_activate(struct kvm_vcpu *vcpu) @@ -2127,6 +2124,8 @@ again: if (unlikely(r)) goto out; + preempt_disable(); + if (!vcpu->mmio_read_completed) do_interrupt_requests(vcpu, kvm_run); @@ -2269,6 +2268,9 @@ again: vcpu->interrupt_window_open = (vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) & 3) == 0; asm ("mov %0, %%ds; mov %0, %%es" : : "r"(__USER_DS)); + vmx->launched = 1; + + preempt_enable(); if (unlikely(fail)) { kvm_run->exit_reason = KVM_EXIT_FAIL_ENTRY; @@ -2283,7 +2285,6 @@ again: if (unlikely(prof_on == KVM_PROFILING)) profile_hit(KVM_PROFILING, (void *)vmcs_readl(GUEST_RIP)); - vmx->launched = 1; r = kvm_handle_exit(kvm_run, vcpu); if (r > 0) { /* Give scheduler a change to reschedule. */ @@ -2372,6 +2373,7 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id) { int err; struct vcpu_vmx *vmx = kzalloc(sizeof(*vmx), GFP_KERNEL); + int cpu; if (!vmx) return ERR_PTR(-ENOMEM); @@ -2396,9 +2398,11 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id) vmcs_clear(vmx->vmcs); - vmx_vcpu_load(&vmx->vcpu); + cpu = get_cpu(); + vmx_vcpu_load(&vmx->vcpu, cpu); err = vmx_vcpu_setup(&vmx->vcpu); vmx_vcpu_put(&vmx->vcpu); + put_cpu(); if (err) goto free_vmcs; -- cgit v1.2.3