From 2e4682ba2ed79d8082b78d292b3b80f54d970b7a Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Thu, 10 Mar 2016 16:30:22 +0100 Subject: KVM: add missing memory barrier in kvm_{make,check}_request kvm_make_request and kvm_check_request imply a producer-consumer relationship; add implicit memory barriers to them. There was indeed already a place that was adding an explicit smp_mb() to order between kvm_check_request and the processing of the request. That memory barrier can be removed (as an added benefit, kvm_check_request can use smp_mb__after_atomic which is free on x86). Signed-off-by: Paolo Bonzini --- include/linux/kvm_host.h | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'include/linux/kvm_host.h') diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 5276fe0916fc..ad40d44784c7 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1091,6 +1091,11 @@ static inline bool kvm_vcpu_compatible(struct kvm_vcpu *vcpu) { return true; } static inline void kvm_make_request(int req, struct kvm_vcpu *vcpu) { + /* + * Ensure the rest of the request is published to kvm_check_request's + * caller. Paired with the smp_mb__after_atomic in kvm_check_request. + */ + smp_wmb(); set_bit(req, &vcpu->requests); } @@ -1098,6 +1103,12 @@ static inline bool kvm_check_request(int req, struct kvm_vcpu *vcpu) { if (test_bit(req, &vcpu->requests)) { clear_bit(req, &vcpu->requests); + + /* + * Ensure the rest of the request is visible to kvm_check_request's + * caller. Paired with the smp_wmb in kvm_make_request. + */ + smp_mb__after_atomic(); return true; } else { return false; -- cgit v1.2.3 From 9b9e3fc4d5a31f6050508f2404369beac4356867 Mon Sep 17 00:00:00 2001 From: Greg Kurz Date: Mon, 9 May 2016 18:11:54 +0200 Subject: KVM: remove NULL return path for vcpu ids >= KVM_MAX_VCPUS Commit c896939f7cff ("KVM: use heuristic for fast VCPU lookup by id") added a return path that prevents vcpu ids to exceed KVM_MAX_VCPUS. This is a problem for powerpc where vcpu ids can grow up to 8*KVM_MAX_VCPUS. This patch simply reverses the logic so that we only try fast path if the vcpu id can be tried as an index in kvm->vcpus[]. The slow path is not affected by the change. Reviewed-by: David Hildenbrand Reviewed-by: Cornelia Huck Signed-off-by: Greg Kurz Signed-off-by: Paolo Bonzini --- include/linux/kvm_host.h | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'include/linux/kvm_host.h') diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index ad40d44784c7..0a0e00d9c5da 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -447,12 +447,13 @@ static inline struct kvm_vcpu *kvm_get_vcpu(struct kvm *kvm, int i) static inline struct kvm_vcpu *kvm_get_vcpu_by_id(struct kvm *kvm, int id) { - struct kvm_vcpu *vcpu; + struct kvm_vcpu *vcpu = NULL; int i; - if (id < 0 || id >= KVM_MAX_VCPUS) + if (id < 0) return NULL; - vcpu = kvm_get_vcpu(kvm, id); + if (id < KVM_MAX_VCPUS) + vcpu = kvm_get_vcpu(kvm, id); if (vcpu && vcpu->vcpu_id == id) return vcpu; kvm_for_each_vcpu(i, vcpu, kvm) -- cgit v1.2.3 From 0b1b1dfd52a67f4f09a18cb82337199bc90ad7fb Mon Sep 17 00:00:00 2001 From: Greg Kurz Date: Mon, 9 May 2016 18:13:37 +0200 Subject: kvm: introduce KVM_MAX_VCPU_ID The KVM_MAX_VCPUS define provides the maximum number of vCPUs per guest, and also the upper limit for vCPU ids. This is okay for all archs except PowerPC which can have higher ids, depending on the cpu/core/thread topology. In the worst case (single threaded guest, host with 8 threads per core), it limits the maximum number of vCPUS to KVM_MAX_VCPUS / 8. This patch separates the vCPU numbering from the total number of vCPUs, with the introduction of KVM_MAX_VCPU_ID, as the maximal valid value for vCPU ids plus one. The corresponding KVM_CAP_MAX_VCPU_ID allows userspace to validate vCPU ids before passing them to KVM_CREATE_VCPU. This patch only implements KVM_MAX_VCPU_ID with a specific value for PowerPC. Other archs continue to return KVM_MAX_VCPUS instead. Suggested-by: Radim Krcmar Signed-off-by: Greg Kurz Reviewed-by: Cornelia Huck Signed-off-by: Paolo Bonzini --- include/linux/kvm_host.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'include/linux/kvm_host.h') diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 0a0e00d9c5da..352889d6e322 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -35,6 +35,10 @@ #include +#ifndef KVM_MAX_VCPU_ID +#define KVM_MAX_VCPU_ID KVM_MAX_VCPUS +#endif + /* * The bit 16 ~ bit 31 of kvm_memory_region::flags are internally used * in kvm, other bits are visible for userspace which are defined in -- cgit v1.2.3 From 14717e2031862d9aa2512b24a7df42cf68a977ec Mon Sep 17 00:00:00 2001 From: Alex Williamson Date: Thu, 5 May 2016 11:58:35 -0600 Subject: kvm: Conditionally register IRQ bypass consumer If we don't support a mechanism for bypassing IRQs, don't register as a consumer. This eliminates meaningless dev_info()s when the connect fails between producer and consumer, such as on AMD systems where kvm_x86_ops->update_pi_irte is not implemented Signed-off-by: Alex Williamson Signed-off-by: Paolo Bonzini --- include/linux/kvm_host.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/kvm_host.h') diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 352889d6e322..92a0229044fb 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1185,6 +1185,7 @@ static inline void kvm_vcpu_set_dy_eligible(struct kvm_vcpu *vcpu, bool val) #endif /* CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT */ #ifdef CONFIG_HAVE_KVM_IRQ_BYPASS +bool kvm_arch_has_irq_bypass(void); int kvm_arch_irq_bypass_add_producer(struct irq_bypass_consumer *, struct irq_bypass_producer *); void kvm_arch_irq_bypass_del_producer(struct irq_bypass_consumer *, -- cgit v1.2.3 From 3491caf2755e9f312666712510d80b00c81ff247 Mon Sep 17 00:00:00 2001 From: Christian Borntraeger Date: Fri, 13 May 2016 12:16:35 +0200 Subject: KVM: halt_polling: provide a way to qualify wakeups during poll MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Some wakeups should not be considered a sucessful poll. For example on s390 I/O interrupts are usually floating, which means that _ALL_ CPUs would be considered runnable - letting all vCPUs poll all the time for transactional like workload, even if one vCPU would be enough. This can result in huge CPU usage for large guests. This patch lets architectures provide a way to qualify wakeups if they should be considered a good/bad wakeups in regard to polls. For s390 the implementation will fence of halt polling for anything but known good, single vCPU events. The s390 implementation for floating interrupts does a wakeup for one vCPU, but the interrupt will be delivered by whatever CPU checks first for a pending interrupt. We prefer the woken up CPU by marking the poll of this CPU as "good" poll. This code will also mark several other wakeup reasons like IPI or expired timers as "good". This will of course also mark some events as not sucessful. As KVM on z runs always as a 2nd level hypervisor, we prefer to not poll, unless we are really sure, though. This patch successfully limits the CPU usage for cases like uperf 1byte transactional ping pong workload or wakeup heavy workload like OLTP while still providing a proper speedup. This also introduced a new vcpu stat "halt_poll_no_tuning" that marks wakeups that are considered not good for polling. Signed-off-by: Christian Borntraeger Acked-by: Radim Krčmář (for an earlier version) Cc: David Matlack Cc: Wanpeng Li [Rename config symbol. - Paolo] Signed-off-by: Paolo Bonzini --- include/linux/kvm_host.h | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'include/linux/kvm_host.h') diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 92a0229044fb..bbcd921d7cb0 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -229,6 +229,7 @@ struct kvm_vcpu { sigset_t sigset; struct kvm_vcpu_stat stat; unsigned int halt_poll_ns; + bool valid_wakeup; #ifdef CONFIG_HAS_IOMEM int mmio_needed; @@ -1196,4 +1197,18 @@ int kvm_arch_update_irqfd_routing(struct kvm *kvm, unsigned int host_irq, uint32_t guest_irq, bool set); #endif /* CONFIG_HAVE_KVM_IRQ_BYPASS */ +#ifdef CONFIG_HAVE_KVM_INVALID_WAKEUPS +/* If we wakeup during the poll time, was it a sucessful poll? */ +static inline bool vcpu_valid_wakeup(struct kvm_vcpu *vcpu) +{ + return vcpu->valid_wakeup; +} + +#else +static inline bool vcpu_valid_wakeup(struct kvm_vcpu *vcpu) +{ + return true; +} +#endif /* CONFIG_HAVE_KVM_INVALID_WAKEUPS */ + #endif -- cgit v1.2.3 From dd1a4cc1fbdf516bb38ca31b65c76e720d414d0d Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= Date: Wed, 4 May 2016 14:09:44 -0500 Subject: KVM: split kvm_vcpu_wake_up from kvm_vcpu_kick MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit AVIC has a use for kvm_vcpu_wake_up. Signed-off-by: Radim Krčmář Tested-by: Suravee Suthikulpanit Reviewed-by: Paolo Bonzini Signed-off-by: Paolo Bonzini --- include/linux/kvm_host.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/kvm_host.h') diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index bbcd921d7cb0..b1fa8f11c95b 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -657,6 +657,7 @@ void kvm_vcpu_mark_page_dirty(struct kvm_vcpu *vcpu, gfn_t gfn); void kvm_vcpu_block(struct kvm_vcpu *vcpu); void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu); void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu); +void kvm_vcpu_wake_up(struct kvm_vcpu *vcpu); void kvm_vcpu_kick(struct kvm_vcpu *vcpu); int kvm_vcpu_yield_to(struct kvm_vcpu *target); void kvm_vcpu_on_spin(struct kvm_vcpu *vcpu); -- cgit v1.2.3 From 536a6f88c49dd739961ffd53774775afed852c83 Mon Sep 17 00:00:00 2001 From: Janosch Frank Date: Wed, 18 May 2016 13:26:23 +0200 Subject: KVM: Create debugfs dir and stat files for each VM This patch adds a kvm debugfs subdirectory for each VM, which is named after its pid and file descriptor. The directories contain the same kind of files that are already in the kvm debugfs directory, but the data exported through them is now VM specific. This makes the debugfs kvm data a convenient alternative to the tracepoints which already have per VM data. The debugfs data is easy to read and low overhead. CC: Dan Carpenter [includes fixes by Dan Carpenter] Signed-off-by: Janosch Frank Signed-off-by: Paolo Bonzini --- include/linux/kvm_host.h | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'include/linux/kvm_host.h') diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index b1fa8f11c95b..1c9c973a7dd9 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -412,6 +412,8 @@ struct kvm { #endif long tlbs_dirty; struct list_head devices; + struct dentry *debugfs_dentry; + struct kvm_stat_data **debugfs_stat_data; }; #define kvm_err(fmt, ...) \ @@ -991,6 +993,11 @@ enum kvm_stat_kind { KVM_STAT_VCPU, }; +struct kvm_stat_data { + int offset; + struct kvm *kvm; +}; + struct kvm_stats_debugfs_item { const char *name; int offset; -- cgit v1.2.3