From mboxrd@z Thu Jan 1 00:00:00 1970 From: andre.przywara@arm.com (Andre Przywara) Date: Wed, 17 Jun 2015 12:21:58 +0100 Subject: [PATCH v3 07/10] limit number of VCPUs on demand In-Reply-To: <1434540121-21283-1-git-send-email-andre.przywara@arm.com> References: <1434540121-21283-1-git-send-email-andre.przywara@arm.com> Message-ID: <1434540121-21283-8-git-send-email-andre.przywara@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Currently the ARM GIC checks the number of VCPUs against a fixed limit, which is GICv2 specific. Don't pretend we know better than the kernel and let's get rid of that explicit check. Instead be more relaxed about KVM_CREATE_VCPU failing with EINVAL, which is the way the kernel communicates having reached a VCPU limit. If we see this and have at least brought up one VCPU already successfully, then don't panic, but limit the number of VCPUs instead. Signed-off-by: Andre Przywara --- arm/gic.c | 6 ------ arm/kvm-cpu.c | 11 +++++++++-- kvm-cpu.c | 7 +++++++ 3 files changed, 16 insertions(+), 8 deletions(-) diff --git a/arm/gic.c b/arm/gic.c index 99f0d2b..05f85a2 100644 --- a/arm/gic.c +++ b/arm/gic.c @@ -84,12 +84,6 @@ int gic__create(struct kvm *kvm) { int err; - if (kvm->nrcpus > GIC_MAX_CPUS) { - pr_warning("%d CPUS greater than maximum of %d -- truncating\n", - kvm->nrcpus, GIC_MAX_CPUS); - kvm->nrcpus = GIC_MAX_CPUS; - } - /* Try the new way first, and fallback on legacy method otherwise */ err = gic__create_device(kvm); if (err) diff --git a/arm/kvm-cpu.c b/arm/kvm-cpu.c index 7780251..c1cf51d 100644 --- a/arm/kvm-cpu.c +++ b/arm/kvm-cpu.c @@ -47,12 +47,19 @@ struct kvm_cpu *kvm_cpu__arch_init(struct kvm *kvm, unsigned long cpu_id) }; vcpu = calloc(1, sizeof(struct kvm_cpu)); - if (!vcpu) + if (!vcpu) { + errno = ENOMEM; return NULL; + } vcpu->vcpu_fd = ioctl(kvm->vm_fd, KVM_CREATE_VCPU, cpu_id); - if (vcpu->vcpu_fd < 0) + if (vcpu->vcpu_fd < 0) { + if (errno == EINVAL) { + free(vcpu); + return NULL; + } die_perror("KVM_CREATE_VCPU ioctl"); + } mmap_size = ioctl(kvm->sys_fd, KVM_GET_VCPU_MMAP_SIZE, 0); if (mmap_size < 0) diff --git a/kvm-cpu.c b/kvm-cpu.c index 5d90664..7a9d689 100644 --- a/kvm-cpu.c +++ b/kvm-cpu.c @@ -222,11 +222,18 @@ int kvm_cpu__init(struct kvm *kvm) for (i = 0; i < kvm->nrcpus; i++) { kvm->cpus[i] = kvm_cpu__arch_init(kvm, i); if (!kvm->cpus[i]) { + if (i > 0 && errno == EINVAL) + break; pr_warning("unable to initialize KVM VCPU"); goto fail_alloc; } } + if (i < kvm->nrcpus) { + kvm->nrcpus = i; + printf(" # The kernel limits the number of CPUs to %d\n", i); + } + return 0; fail_alloc: -- 2.3.5 From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andre Przywara Subject: [PATCH v3 07/10] limit number of VCPUs on demand Date: Wed, 17 Jun 2015 12:21:58 +0100 Message-ID: <1434540121-21283-8-git-send-email-andre.przywara@arm.com> References: <1434540121-21283-1-git-send-email-andre.przywara@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id B408755D05 for ; Wed, 17 Jun 2015 07:11:26 -0400 (EDT) Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id zzfgZm46jhLx for ; Wed, 17 Jun 2015 07:11:24 -0400 (EDT) Received: from foss.arm.com (foss.arm.com [217.140.101.70]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 6F8AC55CFC for ; Wed, 17 Jun 2015 07:11:20 -0400 (EDT) In-Reply-To: <1434540121-21283-1-git-send-email-andre.przywara@arm.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu To: will.deacon@arm.com, marc.zyngier@arm.com Cc: penberg@kernel.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org List-Id: kvmarm@lists.cs.columbia.edu Currently the ARM GIC checks the number of VCPUs against a fixed limit, which is GICv2 specific. Don't pretend we know better than the kernel and let's get rid of that explicit check. Instead be more relaxed about KVM_CREATE_VCPU failing with EINVAL, which is the way the kernel communicates having reached a VCPU limit. If we see this and have at least brought up one VCPU already successfully, then don't panic, but limit the number of VCPUs instead. Signed-off-by: Andre Przywara --- arm/gic.c | 6 ------ arm/kvm-cpu.c | 11 +++++++++-- kvm-cpu.c | 7 +++++++ 3 files changed, 16 insertions(+), 8 deletions(-) diff --git a/arm/gic.c b/arm/gic.c index 99f0d2b..05f85a2 100644 --- a/arm/gic.c +++ b/arm/gic.c @@ -84,12 +84,6 @@ int gic__create(struct kvm *kvm) { int err; - if (kvm->nrcpus > GIC_MAX_CPUS) { - pr_warning("%d CPUS greater than maximum of %d -- truncating\n", - kvm->nrcpus, GIC_MAX_CPUS); - kvm->nrcpus = GIC_MAX_CPUS; - } - /* Try the new way first, and fallback on legacy method otherwise */ err = gic__create_device(kvm); if (err) diff --git a/arm/kvm-cpu.c b/arm/kvm-cpu.c index 7780251..c1cf51d 100644 --- a/arm/kvm-cpu.c +++ b/arm/kvm-cpu.c @@ -47,12 +47,19 @@ struct kvm_cpu *kvm_cpu__arch_init(struct kvm *kvm, unsigned long cpu_id) }; vcpu = calloc(1, sizeof(struct kvm_cpu)); - if (!vcpu) + if (!vcpu) { + errno = ENOMEM; return NULL; + } vcpu->vcpu_fd = ioctl(kvm->vm_fd, KVM_CREATE_VCPU, cpu_id); - if (vcpu->vcpu_fd < 0) + if (vcpu->vcpu_fd < 0) { + if (errno == EINVAL) { + free(vcpu); + return NULL; + } die_perror("KVM_CREATE_VCPU ioctl"); + } mmap_size = ioctl(kvm->sys_fd, KVM_GET_VCPU_MMAP_SIZE, 0); if (mmap_size < 0) diff --git a/kvm-cpu.c b/kvm-cpu.c index 5d90664..7a9d689 100644 --- a/kvm-cpu.c +++ b/kvm-cpu.c @@ -222,11 +222,18 @@ int kvm_cpu__init(struct kvm *kvm) for (i = 0; i < kvm->nrcpus; i++) { kvm->cpus[i] = kvm_cpu__arch_init(kvm, i); if (!kvm->cpus[i]) { + if (i > 0 && errno == EINVAL) + break; pr_warning("unable to initialize KVM VCPU"); goto fail_alloc; } } + if (i < kvm->nrcpus) { + kvm->nrcpus = i; + printf(" # The kernel limits the number of CPUs to %d\n", i); + } + return 0; fail_alloc: -- 2.3.5