The KVM_GUEST_PAUSED flag will prevent a guest from compaining about a soft lockup but it can mask real soft lockups if the flag isn't cleared when it is no longer relevant. This patch adds a kvm ioctl that the hypervisor will use when it resumes a guest to start a timer for aging out the flag. The time out will be specified by the hypervisor in the ioctl call.
Signed-off-by: Eric B Munson <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] --- Changes from V2: Move function definition to kvm_host.h arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/x86.c | 32 ++++++++++++++++++++++++++++++++ include/linux/kvm.h | 2 ++ include/linux/kvm_host.h | 2 ++ 4 files changed, 37 insertions(+), 0 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index beb94c6..5cec925 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -673,6 +673,7 @@ int kvm_pv_mmu_op(struct kvm_vcpu *vcpu, unsigned long bytes, u8 kvm_get_guest_memory_type(struct kvm_vcpu *vcpu, gfn_t gfn); int kvm_set_guest_paused(struct kvm_vcpu *vcpu); +void kvm_clear_guest_paused(struct kvm_vcpu *vcpu, unsigned int length); extern bool tdp_enabled; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 0127617..ca2187b 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -46,6 +46,7 @@ #include <linux/hash.h> #include <linux/pci.h> #include <trace/events/kvm.h> +#include <linux/timer.h> #define CREATE_TRACE_POINTS #include "trace.h" @@ -3299,6 +3300,15 @@ long kvm_arch_vcpu_ioctl(struct file *filp, r = kvm_set_guest_paused(vcpu); break; } + case KVM_CLEAR_GUEST_PAUSED: { + unsigned int length; + r = -EFAULT; + if (copy_from_user(&length, argp, sizeof length)) + goto out; + r = 0; + kvm_clear_guest_paused(vcpu, length); + break; + } default: r = -EINVAL; } @@ -6137,6 +6147,28 @@ int kvm_set_guest_paused(struct kvm_vcpu *vcpu) } EXPORT_SYMBOL_GPL(kvm_set_guest_paused); +static void kvm_timer_clear_guest_paused(unsigned long vcpu_addr) +{ + struct kvm_vcpu *vcpu = (struct kvm_vcpu *)vcpu_addr; + struct pvclock_vcpu_time_info *src = &vcpu->arch.hv_clock; + src->flags = src->flags & (~PVCLOCK_GUEST_STOPPED); +} + +/* + * Host has resumed the guest, we need to clear the guest paused flag so we + * don't mask any real soft lockups. + */ +void kvm_clear_guest_paused(struct kvm_vcpu *vcpu, unsigned int length) +{ + if (!timer_pending(&vcpu->flag_timer)) + setup_timer(&vcpu->flag_timer, + kvm_timer_clear_guest_paused, + (unsigned long)vcpu); + mod_timer(&vcpu->flag_timer, + jiffies + (length * HZ)); +} +EXPORT_SYMBOL_GPL(kvm_clear_guest_paused); + int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs) { diff --git a/include/linux/kvm.h b/include/linux/kvm.h index 87cab0d..bd9724c 100644 --- a/include/linux/kvm.h +++ b/include/linux/kvm.h @@ -765,6 +765,8 @@ struct kvm_clock_data { #define KVM_ALLOCATE_RMA _IOR(KVMIO, 0xa9, struct kvm_allocate_rma) /* VM is being stopped by host */ #define KVM_GUEST_PAUSED _IO(KVMIO, 0xaa) +/* Start the timer to clear the paused flag */ +#define KVM_CLEAR_GUEST_PAUSED _IO(KVMIO, 0xab) #define KVM_DEV_ASSIGN_ENABLE_IOMMU (1 << 0) diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index d526231..043af4d 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -19,6 +19,7 @@ #include <linux/slab.h> #include <linux/rcupdate.h> #include <linux/ratelimit.h> +#include <linux/timer.h> #include <asm/signal.h> #include <linux/kvm.h> @@ -154,6 +155,7 @@ struct kvm_vcpu { #endif struct kvm_vcpu_arch arch; + struct timer_list flag_timer; }; static inline int kvm_vcpu_exiting_guest_mode(struct kvm_vcpu *vcpu) -- 1.7.5.4 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
