From: Jason Wang <jasowang@redhat.com>
To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: Elena Afanasova <eafanasova@gmail.com>,
kvm@vger.kernel.org, jag.raman@oracle.com,
elena.ufimtseva@oracle.com
Subject: Re: [RESEND RFC v2 1/4] KVM: add initial support for KVM_SET_IOREGION
Date: Thu, 18 Feb 2021 14:17:23 +0800 [thread overview]
Message-ID: <c39c5d1a-9977-03a5-689a-ba5de3997fd3@redhat.com> (raw)
In-Reply-To: <20210209145932.GB92126@stefanha-x1.localdomain>
On 2021/2/9 下午10:59, Stefan Hajnoczi wrote:
> On Mon, Feb 08, 2021 at 02:21:35PM +0800, Jason Wang wrote:
>> On 2021/1/30 上午2:48, Elena Afanasova wrote:
>>> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
>>> index ca41220b40b8..81e775778c66 100644
>>> --- a/include/uapi/linux/kvm.h
>>> +++ b/include/uapi/linux/kvm.h
>>> @@ -732,6 +732,27 @@ struct kvm_ioeventfd {
>>> __u8 pad[36];
>>> };
>>> +enum {
>>> + kvm_ioregion_flag_nr_pio,
>>> + kvm_ioregion_flag_nr_posted_writes,
>>> + kvm_ioregion_flag_nr_max,
>>> +};
>>> +
>>> +#define KVM_IOREGION_PIO (1 << kvm_ioregion_flag_nr_pio)
>>> +#define KVM_IOREGION_POSTED_WRITES (1 << kvm_ioregion_flag_nr_posted_writes)
>>> +
>>> +#define KVM_IOREGION_VALID_FLAG_MASK ((1 << kvm_ioregion_flag_nr_max) - 1)
>>> +
>>> +struct kvm_ioregion {
>>> + __u64 guest_paddr; /* guest physical address */
>>> + __u64 memory_size; /* bytes */
>>
>> Do we really need __u64 here?
> I think 64-bit PCI BARs can be >4 GB. There is plenty of space in this
> struct to support a 64-bit field.
>
> That said, userspace could also add more ioregions if it needs to cover
> more than 4 GB. That would slow down ioregion lookups though since the
> in-kernel data structure would become larger.
>
> Making it 64-bit seems more future-proof and cleaner than having to work
> around the limitation using multiple ioregions. Did you have a
> particular reason in mind why this field should not be 64 bits?
Nope. Just wonder what's the use case for that.
Thanks
next prev parent reply other threads:[~2021-02-18 6:25 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-28 18:32 [RFC v2 0/4] Introduce MMIO/PIO dispatch file descriptors (ioregionfd) Elena Afanasova
2021-01-28 18:32 ` [RFC v2 2/4] KVM: x86: add support for ioregionfd signal handling Elena Afanasova
2021-01-30 16:58 ` Stefan Hajnoczi
2021-02-03 14:00 ` Elena Afanasova
2021-02-09 6:21 ` Jason Wang
2021-02-09 14:49 ` Stefan Hajnoczi
2021-02-10 19:06 ` Elena Afanasova
2021-02-09 6:26 ` Jason Wang
2021-01-28 18:32 ` [RFC v2 3/4] KVM: add support for ioregionfd cmds/replies serialization Elena Afanasova
2021-01-30 18:54 ` Stefan Hajnoczi
2021-02-03 14:10 ` Elena Afanasova
2021-01-28 18:32 ` [RFC v2 4/4] KVM: enforce NR_IOBUS_DEVS limit if kmemcg is disabled Elena Afanasova
2021-01-29 18:48 ` [RESEND RFC v2 1/4] KVM: add initial support for KVM_SET_IOREGION Elena Afanasova
2021-01-30 15:04 ` Stefan Hajnoczi
2021-02-04 13:03 ` Cornelia Huck
2021-02-05 18:39 ` Elena Afanasova
2021-02-08 11:49 ` Cornelia Huck
2021-02-08 6:21 ` Jason Wang
2021-02-09 14:59 ` Stefan Hajnoczi
2021-02-18 6:17 ` Jason Wang [this message]
2021-02-10 19:31 ` Elena Afanasova
2021-02-11 14:59 ` Stefan Hajnoczi
2021-02-17 23:05 ` Elena Afanasova
2021-02-18 6:22 ` Jason Wang
2021-02-18 6:20 ` Jason Wang
2021-01-30 14:56 ` [RFC v2 0/4] Introduce MMIO/PIO dispatch file descriptors (ioregionfd) Stefan Hajnoczi
2021-02-02 14:59 ` Stefan Hajnoczi
2021-02-08 6:02 ` Jason Wang
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=c39c5d1a-9977-03a5-689a-ba5de3997fd3@redhat.com \
--to=jasowang@redhat.com \
--cc=eafanasova@gmail.com \
--cc=elena.ufimtseva@oracle.com \
--cc=jag.raman@oracle.com \
--cc=kvm@vger.kernel.org \
--cc=stefanha@redhat.com \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
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).