From: Marc Zyngier <maz@kernel.org> To: kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org Cc: will@kernel.org, catalin.marinas@arm.com, andrew.jones@linux.dev, shan.gavin@gmail.com, bgardon@google.com, dmatlack@google.com, pbonzini@redhat.com, zhenyzha@redhat.com, shuah@kernel.org Subject: [PATCH v2 2/6] KVM: Add KVM_CAP_DIRTY_LOG_RING_ACQ_REL capability and config option Date: Mon, 26 Sep 2022 15:51:16 +0100 [thread overview] Message-ID: <20220926145120.27974-3-maz@kernel.org> (raw) In-Reply-To: <20220926145120.27974-1-maz@kernel.org> In order to differenciate between architectures that require no extra synchronisation when accessing the dirty ring and those who do, add a new capability (KVM_CAP_DIRTY_LOG_RING_ACQ_REL) that identify the latter sort. TSO architectures can obviously advertise both, while relaxed architectures must only advertise the ACQ_REL version. This requires some configuration symbol rejigging, with HAVE_KVM_DIRTY_RING being only indirectly selected by two top-level config symbols: - HAVE_KVM_DIRTY_RING_TSO for strongly ordered architectures (x86) - HAVE_KVM_DIRTY_RING_ACQ_REL for weakly ordered architectures (arm64) Suggested-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Marc Zyngier <maz@kernel.org> --- arch/x86/kvm/Kconfig | 2 +- include/uapi/linux/kvm.h | 1 + virt/kvm/Kconfig | 14 ++++++++++++++ virt/kvm/kvm_main.c | 9 ++++++++- 4 files changed, 24 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig index e3cbd7706136..876748b236ff 100644 --- a/arch/x86/kvm/Kconfig +++ b/arch/x86/kvm/Kconfig @@ -28,7 +28,7 @@ config KVM select HAVE_KVM_IRQCHIP select HAVE_KVM_PFNCACHE select HAVE_KVM_IRQFD - select HAVE_KVM_DIRTY_RING + select HAVE_KVM_DIRTY_RING_TSO select IRQ_BYPASS_MANAGER select HAVE_KVM_IRQ_BYPASS select HAVE_KVM_IRQ_ROUTING diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index eed0315a77a6..0d5d4419139a 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -1177,6 +1177,7 @@ struct kvm_ppc_resize_hpt { #define KVM_CAP_VM_DISABLE_NX_HUGE_PAGES 220 #define KVM_CAP_S390_ZPCI_OP 221 #define KVM_CAP_S390_CPU_TOPOLOGY 222 +#define KVM_CAP_DIRTY_LOG_RING_ACQ_REL 223 #ifdef KVM_CAP_IRQ_ROUTING diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig index a8c5c9f06b3c..800f9470e36b 100644 --- a/virt/kvm/Kconfig +++ b/virt/kvm/Kconfig @@ -19,6 +19,20 @@ config HAVE_KVM_IRQ_ROUTING config HAVE_KVM_DIRTY_RING bool +# Only strongly ordered architectures can select this, as it doesn't +# put any explicit constraint on userspace ordering. They can also +# select the _ACQ_REL version. +config HAVE_KVM_DIRTY_RING_TSO + bool + select HAVE_KVM_DIRTY_RING + depends on X86 + +# Weakly ordered architectures can only select this, advertising +# to userspace the additional ordering requirements. +config HAVE_KVM_DIRTY_RING_ACQ_REL + bool + select HAVE_KVM_DIRTY_RING + config HAVE_KVM_EVENTFD bool select EVENTFD diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 584a5bab3af3..5b064dbadaf4 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -4475,7 +4475,13 @@ static long kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg) case KVM_CAP_NR_MEMSLOTS: return KVM_USER_MEM_SLOTS; case KVM_CAP_DIRTY_LOG_RING: -#ifdef CONFIG_HAVE_KVM_DIRTY_RING +#ifdef CONFIG_HAVE_KVM_DIRTY_RING_TSO + return KVM_DIRTY_RING_MAX_ENTRIES * sizeof(struct kvm_dirty_gfn); +#else + return 0; +#endif + case KVM_CAP_DIRTY_LOG_RING_ACQ_REL: +#ifdef CONFIG_HAVE_KVM_DIRTY_RING_ACQ_REL return KVM_DIRTY_RING_MAX_ENTRIES * sizeof(struct kvm_dirty_gfn); #else return 0; @@ -4580,6 +4586,7 @@ static int kvm_vm_ioctl_enable_cap_generic(struct kvm *kvm, return 0; } case KVM_CAP_DIRTY_LOG_RING: + case KVM_CAP_DIRTY_LOG_RING_ACQ_REL: return kvm_vm_ioctl_enable_dirty_log_ring(kvm, cap->args[0]); default: return kvm_vm_ioctl_enable_cap(kvm, cap); -- 2.34.1 _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
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From: Marc Zyngier <maz@kernel.org> To: kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org Cc: catalin.marinas@arm.com, bgardon@google.com, shuah@kernel.org, andrew.jones@linux.dev, will@kernel.org, dmatlack@google.com, peterx@redhat.com, pbonzini@redhat.com, zhenyzha@redhat.com, shan.gavin@gmail.com, gshan@redhat.com, James Morse <james.morse@arm.com>, Suzuki K Poulose <suzuki.poulose@arm.com>, Alexandru Elisei <alexandru.elisei@arm.com>, Oliver Upton <oliver.upton@linux.dev> Subject: [PATCH v2 2/6] KVM: Add KVM_CAP_DIRTY_LOG_RING_ACQ_REL capability and config option Date: Mon, 26 Sep 2022 15:51:16 +0100 [thread overview] Message-ID: <20220926145120.27974-3-maz@kernel.org> (raw) In-Reply-To: <20220926145120.27974-1-maz@kernel.org> In order to differenciate between architectures that require no extra synchronisation when accessing the dirty ring and those who do, add a new capability (KVM_CAP_DIRTY_LOG_RING_ACQ_REL) that identify the latter sort. TSO architectures can obviously advertise both, while relaxed architectures must only advertise the ACQ_REL version. This requires some configuration symbol rejigging, with HAVE_KVM_DIRTY_RING being only indirectly selected by two top-level config symbols: - HAVE_KVM_DIRTY_RING_TSO for strongly ordered architectures (x86) - HAVE_KVM_DIRTY_RING_ACQ_REL for weakly ordered architectures (arm64) Suggested-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Marc Zyngier <maz@kernel.org> --- arch/x86/kvm/Kconfig | 2 +- include/uapi/linux/kvm.h | 1 + virt/kvm/Kconfig | 14 ++++++++++++++ virt/kvm/kvm_main.c | 9 ++++++++- 4 files changed, 24 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig index e3cbd7706136..876748b236ff 100644 --- a/arch/x86/kvm/Kconfig +++ b/arch/x86/kvm/Kconfig @@ -28,7 +28,7 @@ config KVM select HAVE_KVM_IRQCHIP select HAVE_KVM_PFNCACHE select HAVE_KVM_IRQFD - select HAVE_KVM_DIRTY_RING + select HAVE_KVM_DIRTY_RING_TSO select IRQ_BYPASS_MANAGER select HAVE_KVM_IRQ_BYPASS select HAVE_KVM_IRQ_ROUTING diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index eed0315a77a6..0d5d4419139a 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -1177,6 +1177,7 @@ struct kvm_ppc_resize_hpt { #define KVM_CAP_VM_DISABLE_NX_HUGE_PAGES 220 #define KVM_CAP_S390_ZPCI_OP 221 #define KVM_CAP_S390_CPU_TOPOLOGY 222 +#define KVM_CAP_DIRTY_LOG_RING_ACQ_REL 223 #ifdef KVM_CAP_IRQ_ROUTING diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig index a8c5c9f06b3c..800f9470e36b 100644 --- a/virt/kvm/Kconfig +++ b/virt/kvm/Kconfig @@ -19,6 +19,20 @@ config HAVE_KVM_IRQ_ROUTING config HAVE_KVM_DIRTY_RING bool +# Only strongly ordered architectures can select this, as it doesn't +# put any explicit constraint on userspace ordering. They can also +# select the _ACQ_REL version. +config HAVE_KVM_DIRTY_RING_TSO + bool + select HAVE_KVM_DIRTY_RING + depends on X86 + +# Weakly ordered architectures can only select this, advertising +# to userspace the additional ordering requirements. +config HAVE_KVM_DIRTY_RING_ACQ_REL + bool + select HAVE_KVM_DIRTY_RING + config HAVE_KVM_EVENTFD bool select EVENTFD diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 584a5bab3af3..5b064dbadaf4 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -4475,7 +4475,13 @@ static long kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg) case KVM_CAP_NR_MEMSLOTS: return KVM_USER_MEM_SLOTS; case KVM_CAP_DIRTY_LOG_RING: -#ifdef CONFIG_HAVE_KVM_DIRTY_RING +#ifdef CONFIG_HAVE_KVM_DIRTY_RING_TSO + return KVM_DIRTY_RING_MAX_ENTRIES * sizeof(struct kvm_dirty_gfn); +#else + return 0; +#endif + case KVM_CAP_DIRTY_LOG_RING_ACQ_REL: +#ifdef CONFIG_HAVE_KVM_DIRTY_RING_ACQ_REL return KVM_DIRTY_RING_MAX_ENTRIES * sizeof(struct kvm_dirty_gfn); #else return 0; @@ -4580,6 +4586,7 @@ static int kvm_vm_ioctl_enable_cap_generic(struct kvm *kvm, return 0; } case KVM_CAP_DIRTY_LOG_RING: + case KVM_CAP_DIRTY_LOG_RING_ACQ_REL: return kvm_vm_ioctl_enable_dirty_log_ring(kvm, cap->args[0]); default: return kvm_vm_ioctl_enable_cap(kvm, cap); -- 2.34.1
next prev parent reply other threads:[~2022-09-26 14:51 UTC|newest] Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-09-26 14:51 [PATCH v2 0/6] KVM: Fix dirty-ring ordering on weakly ordered architectures Marc Zyngier 2022-09-26 14:51 ` Marc Zyngier 2022-09-26 14:51 ` [PATCH v2 1/6] KVM: Use acquire/release semantics when accessing dirty ring GFN state Marc Zyngier 2022-09-26 14:51 ` Marc Zyngier 2022-09-26 14:51 ` Marc Zyngier [this message] 2022-09-26 14:51 ` [PATCH v2 2/6] KVM: Add KVM_CAP_DIRTY_LOG_RING_ACQ_REL capability and config option Marc Zyngier 2022-09-26 14:51 ` [PATCH v2 3/6] KVM: x86: Select CONFIG_HAVE_KVM_DIRTY_RING_ACQ_REL Marc Zyngier 2022-09-26 14:51 ` Marc Zyngier 2022-09-26 14:51 ` [PATCH v2 4/6] KVM: Document weakly ordered architecture requirements for dirty ring Marc Zyngier 2022-09-26 14:51 ` Marc Zyngier 2022-09-26 14:51 ` [PATCH v2 5/6] KVM: selftests: dirty-log: Upgrade flag accesses to acquire/release semantics Marc Zyngier 2022-09-26 14:51 ` Marc Zyngier 2022-09-26 14:51 ` [PATCH v2 6/6] KVM: selftests: dirty-log: Use KVM_CAP_DIRTY_LOG_RING_ACQ_REL if available Marc Zyngier 2022-09-26 14:51 ` Marc Zyngier 2022-09-27 0:58 ` [PATCH v2 0/6] KVM: Fix dirty-ring ordering on weakly ordered architectures Gavin Shan 2022-09-27 0:58 ` Gavin Shan 2022-09-27 15:54 ` Peter Xu 2022-09-27 15:54 ` Peter Xu 2022-09-29 9:58 ` Marc Zyngier 2022-09-29 9:58 ` Marc Zyngier
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