From: "Radim Krčmář" <rkrcmar@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Andrew Honig <ahonig@google.com>,
linux-kernel@vger.kernel.org, kvm <kvm@vger.kernel.org>,
"Lan, Tianyu" <tianyu.lan@intel.com>,
Igor Mammedov <imammedo@redhat.com>,
Jan Kiszka <jan.kiszka@web.de>, Peter Xu <peterx@redhat.com>
Subject: Re: [PATCH v1 03/11] KVM: x86: dynamic kvm_apic_map
Date: Fri, 1 Jul 2016 14:44:21 +0200 [thread overview]
Message-ID: <20160701124421.GA2301@potion> (raw)
In-Reply-To: <f483a0a7-08c5-8329-1078-7b00fe7ef404@redhat.com>
2016-07-01 10:42+0200, Paolo Bonzini:
> On 01/07/2016 00:15, Andrew Honig wrote:
>>> > + /* kvm_apic_map_get_logical_dest() expects multiples of 16 */
>>> > + size = round_up(max_id + 1, 16);
>> Now that you're using the full range of apic_id values, could this
>> calculation overflow? Perhaps max_id could be u64?
>
> Good point, but I wonder if it's a good idea to let userspace allocate
> 32 GB of memory. :)
Yes, both could happen. I'll change it to u64 to make it future proof.
> Let's put a limit on the maximum supported APIC ID, and report it
> through KVM_CHECK_EXTENSION on the new KVM_CAP_X2APIC_API capability.
> If 767 is enough for Knights Landing, the allocation below fits in two
> pages. If you need to make it higher, please change the allocation to
> use kvm_kvzalloc and kvfree.
We sort of have a capability for maximum APIC ID, KVM_MAX_VCPU_ID,
because VCPU ID is initial APIC ID and x2APIC ID should always be the
initial APIC ID.
Userspace is able to change x2APIC with LAPIC_GET/SET ioctl -- what
about forbidding that?
> Last but not least...
>
> >> > + new = kzalloc(sizeof(struct kvm_apic_map) +
> >> > + sizeof(struct kvm_lapic) * size, GFP_KERNEL);
> ^^^^^^^^^^^^^^^^^^^^^^^^
> ... the sizeof here must be sizeof(struct kvm_lapic *).
Oops, thanks.
next prev parent reply other threads:[~2016-07-01 12:44 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-30 20:54 [PATCH v1 00/11] KVM: x86: break the xAPIC barrier Radim Krčmář
2016-06-30 20:54 ` [PATCH v1 01/11] KVM: x86: bump KVM_SOFT_MAX_VCPUS to 240 Radim Krčmář
2016-07-01 8:42 ` Paolo Bonzini
2016-06-30 20:54 ` [PATCH v1 02/11] KVM: x86: add kvm_apic_map_get_dest_lapic Radim Krčmář
2016-07-01 7:57 ` Paolo Bonzini
2016-07-01 12:39 ` Radim Krčmář
2016-06-30 20:54 ` [PATCH v1 03/11] KVM: x86: dynamic kvm_apic_map Radim Krčmář
2016-06-30 22:15 ` Andrew Honig
2016-07-01 8:42 ` Paolo Bonzini
2016-07-01 12:44 ` Radim Krčmář [this message]
2016-07-01 14:03 ` Paolo Bonzini
2016-07-01 14:38 ` Radim Krčmář
2016-07-01 15:06 ` Paolo Bonzini
2016-07-01 15:12 ` Paolo Bonzini
2016-07-01 15:43 ` Radim Krčmář
2016-07-01 16:38 ` Paolo Bonzini
2016-07-01 15:35 ` Radim Krčmář
2016-07-01 7:33 ` Paolo Bonzini
2016-06-30 20:54 ` [PATCH v1 04/11] KVM: x86: use u16 for logical VCPU mask in lapic Radim Krčmář
2016-07-01 7:56 ` Paolo Bonzini
2016-07-01 12:48 ` Radim Krčmář
2016-07-01 14:04 ` Paolo Bonzini
2016-06-30 20:54 ` [PATCH v1 05/11] KVM: x86: use generic function for MSI parsing Radim Krčmář
2016-07-01 8:42 ` Paolo Bonzini
2016-06-30 20:54 ` [PATCH v1 06/11] KVM: x86: use hardware-compatible format for APIC ID register Radim Krčmář
2016-07-01 8:33 ` Paolo Bonzini
2016-07-01 13:11 ` Radim Krčmář
2016-07-01 14:12 ` Paolo Bonzini
2016-07-01 14:54 ` Radim Krčmář
2016-07-01 15:07 ` Paolo Bonzini
2016-07-01 15:53 ` Radim Krčmář
2016-07-01 16:37 ` Paolo Bonzini
2016-06-30 20:54 ` [PATCH v1 07/11] KVM: VMX: optimize APIC ID read with APICv Radim Krčmář
2016-07-01 8:42 ` Paolo Bonzini
2016-06-30 20:54 ` [PATCH v1 08/11] KVM: x86: directly call recalculate_apic_map on lapic restore Radim Krčmář
2016-07-01 8:43 ` Paolo Bonzini
2016-06-30 20:54 ` [PATCH v1 09/11] KVM: x86: reset lapic base in kvm_lapic_reset Radim Krčmář
2016-07-01 8:43 ` Paolo Bonzini
2016-06-30 20:54 ` [PATCH v1 10/11] KVM: x86: add KVM_CAP_X2APIC_API Radim Krčmář
2016-07-01 8:24 ` Paolo Bonzini
2016-07-01 13:25 ` Radim Krčmář
2016-07-01 18:09 ` David Matlack
2016-07-01 18:31 ` Radim Krčmář
2016-06-30 20:54 ` [PATCH v1 11/11] KVM: x86: bump MAX_VCPUS to 288 Radim Krčmář
2016-07-01 8:43 ` Paolo Bonzini
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