LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Nitesh Narayan Lal <nitesh@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
mtosatti@redhat.com, vkuznets@redhat.com,
sean.j.christopherson@intel.com, wanpengli@tencent.com,
jmattson@google.com, joro@8bytes.org
Subject: Re: [Patch v1] KVM: x86: Initializing all kvm_lapic_irq fields
Date: Wed, 11 Mar 2020 15:05:59 -0400 [thread overview]
Message-ID: <1ee122a6-7c6a-f630-ea38-9f78960b76be@redhat.com> (raw)
In-Reply-To: <c4370fce-1bc7-3a82-91a7-37fcd013bd77@redhat.com>
[-- Attachment #1.1: Type: text/plain, Size: 2241 bytes --]
On 3/11/20 2:49 PM, Paolo Bonzini wrote:
> On 11/03/20 19:34, Nitesh Narayan Lal wrote:
>> Previously all fields of structure kvm_lapic_irq were not initialized
>> before it was passed to kvm_bitmap_or_dest_vcpus(). Which will cause
>> an issue when any of those fields are used for processing a request.
>> This patch initializes all the fields of kvm_lapic_irq based on the
>> values which are passed through the ioapic redirect_entry object.
> Can you explain better how the bug manifests itself?
For example not initializing the irq.msi_redir_hint field, could lead to a
situation where it carries garbage (non-zero) value.
This will lead to misbehavior of kvm_apic_map_get_dest_lapic() when it invokes
the kvm_lowest_prio_delivery(), that will return true because of non-zero
msi_redir_hint field.
To be on the safe side, I thought of initializing other struct fields as well.
If the above explanation makes sense, I can include it in the patch
subject and send a second version of this patch?
>
> Thanks,
>
> Paolo
>
>> Fixes: 7ee30bc132c6("KVM: x86: deliver KVM IOAPIC scan request to target vCPUs")
>> Signed-off-by: Nitesh Narayan Lal <nitesh@redhat.com>
>> ---
>> arch/x86/kvm/ioapic.c | 7 +++++--
>> 1 file changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/x86/kvm/ioapic.c b/arch/x86/kvm/ioapic.c
>> index 7668fed..3a8467d 100644
>> --- a/arch/x86/kvm/ioapic.c
>> +++ b/arch/x86/kvm/ioapic.c
>> @@ -378,12 +378,15 @@ static void ioapic_write_indirect(struct kvm_ioapic *ioapic, u32 val)
>> if (e->fields.delivery_mode == APIC_DM_FIXED) {
>> struct kvm_lapic_irq irq;
>>
>> - irq.shorthand = APIC_DEST_NOSHORT;
>> irq.vector = e->fields.vector;
>> irq.delivery_mode = e->fields.delivery_mode << 8;
>> - irq.dest_id = e->fields.dest_id;
>> irq.dest_mode =
>> kvm_lapic_irq_dest_mode(!!e->fields.dest_mode);
>> + irq.level = 1;
>> + irq.trig_mode = e->fields.trig_mode;
>> + irq.shorthand = APIC_DEST_NOSHORT;
>> + irq.dest_id = e->fields.dest_id;
>> + irq.msi_redir_hint = false;
>> bitmap_zero(&vcpu_bitmap, 16);
>> kvm_bitmap_or_dest_vcpus(ioapic->kvm, &irq,
>> &vcpu_bitmap);
>>
--
Nitesh
[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 833 bytes --]
prev parent reply other threads:[~2020-03-11 19:06 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-11 18:34 Nitesh Narayan Lal
2020-03-11 18:49 ` Paolo Bonzini
2020-03-11 19:05 ` Nitesh Narayan Lal [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1ee122a6-7c6a-f630-ea38-9f78960b76be@redhat.com \
--to=nitesh@redhat.com \
--cc=jmattson@google.com \
--cc=joro@8bytes.org \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mtosatti@redhat.com \
--cc=pbonzini@redhat.com \
--cc=sean.j.christopherson@intel.com \
--cc=vkuznets@redhat.com \
--cc=wanpengli@tencent.com \
--subject='Re: [Patch v1] KVM: x86: Initializing all kvm_lapic_irq fields' \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).