From: will.deacon@arm•com (Will Deacon)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v4 07/10] limit number of VCPUs on demand
Date: Tue, 30 Jun 2015 17:09:53 +0100 [thread overview]
Message-ID: <20150630160949.GR27725@arm.com> (raw)
In-Reply-To: <1435324578-21832-8-git-send-email-andre.przywara@arm.com>
On Fri, Jun 26, 2015 at 02:16:15PM +0100, Andre Przywara wrote:
> 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 <andre.przywara@arm•com>
> ---
> arm/gic.c | 6 ------
> arm/kvm-cpu.c | 7 ++++++-
> kvm-cpu.c | 7 +++++++
> 3 files changed, 13 insertions(+), 7 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..b2fd6ed 100644
> --- a/arm/kvm-cpu.c
> +++ b/arm/kvm-cpu.c
> @@ -51,8 +51,13 @@ struct kvm_cpu *kvm_cpu__arch_init(struct kvm *kvm, unsigned long cpu_id)
> 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;
> + }
Hmm, but EINVAL can mean all sorts of other failures too, surely? I'm
not against removing the nrcpus check, but I think we should die if ioctls
start failing rather than silently ignore them.
Will
next prev parent reply other threads:[~2015-06-30 16:09 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-26 13:16 [PATCH v4 00/10] kvmtool: arm64: GICv3 guest support Andre Przywara
2015-06-26 13:16 ` [PATCH v4 01/10] AArch64: Reserve two 64k pages for GIC CPU interface Andre Przywara
2015-06-26 13:16 ` [PATCH v4 02/10] AArch{32, 64}: use KVM_CREATE_DEVICE & co to instanciate the GIC Andre Przywara
2015-06-26 13:16 ` [PATCH v4 03/10] irq: add irq__get_nr_allocated_lines Andre Przywara
2015-06-26 13:16 ` [PATCH v4 04/10] AArch{32, 64}: dynamically configure the number of GIC interrupts Andre Przywara
2015-06-26 13:16 ` [PATCH v4 05/10] arm: finish VGIC initialisation explicitly Andre Przywara
2015-06-26 13:16 ` [PATCH v4 06/10] arm: simplify MMIO dispatching Andre Przywara
2015-06-26 13:16 ` [PATCH v4 07/10] limit number of VCPUs on demand Andre Przywara
2015-06-30 16:09 ` Will Deacon [this message]
2015-06-30 16:27 ` Andre Przywara
2015-06-26 13:16 ` [PATCH v4 08/10] arm: prepare for instantiating different IRQ chip devices Andre Przywara
2015-06-26 13:16 ` [PATCH v4 09/10] arm: add support for supplying GICv3 redistributor addresses Andre Przywara
2015-06-26 13:16 ` [PATCH v4 10/10] arm: use new irqchip parameter to create different vGIC types Andre Przywara
2015-06-30 16:13 ` Will Deacon
2015-06-30 16:50 ` Andre Przywara
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