From: "Suthikulpanit, Suravee" <suravee.suthikulpanit@amd.com>
To: Maxim Levitsky <mlevitsk@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: seanjc@google.com, joro@8bytes.org, jon.grimm@amd.com,
wei.huang2@amd.com, terry.bowman@amd.com
Subject: Re: [PATCH v6 15/17] KVM: SVM: Use target APIC ID to complete x2AVIC IRQs when possible
Date: Tue, 28 Jun 2022 09:35:28 +0700 [thread overview]
Message-ID: <9f3ffe16-2516-d4ec-528e-6347ef884ad5@amd.com> (raw)
In-Reply-To: <d761ef283bc91002322f3cd66c124d329c25f04f.camel@redhat.com>
On 6/28/2022 5:55 AM, Maxim Levitsky wrote:
> On Fri, 2022-06-24 at 18:41 +0200, Paolo Bonzini wrote:
>> On 5/19/22 12:27, Suravee Suthikulpanit wrote:
>>> + * If the x2APIC logical ID sub-field (i.e. icrh[15:0]) contains zero
>>> + * or more than 1 bits, we cannot match just one vcpu to kick for
>>> + * fast path.
>>> + */
>>> + if (!first || (first != last))
>>> + return -EINVAL;
>>> +
>>> + apic = first - 1;
>>> + if ((apic < 0) || (apic > 15) || (cluster >= 0xfffff))
>>> + return -EINVAL;
>>
>> Neither of these is possible: first == 0 has been cheked above, and
>> ffs(icrh & 0xffff) cannot exceed 15. Likewise, cluster is actually
>> limited to 16 bits, not 20.
>>
>> Plus, C is not Pascal so no parentheses. :)
>>
>> Putting everything together, it can be simplified to this:
>>
>> + int cluster = (icrh & 0xffff0000) >> 16;
>> + int apic = ffs(icrh & 0xffff) - 1;
>> +
>> + /*
>> + * If the x2APIC logical ID sub-field (i.e. icrh[15:0])
>> + * contains anything but a single bit, we cannot use the
>> + * fast path, because it is limited to a single vCPU.
>> + */
>> + if (apic < 0 || icrh != (1 << apic))
>> + return -EINVAL;
>> +
>> + l1_physical_id = (cluster << 4) + apic;
>>
>>
>>> + apic_id = (cluster << 4) + apic;
>
> Hi Paolo and Suravee Suthikulpanit!
>
> Note that this patch is not needed anymore, I fixed the avic_kick_target_vcpus_fast function,
> and added the support for x2apic because it was very easy to do
> (I already needed to parse logical id for flat and cluser modes)
>
> Best regards,
> Maxim Levitsky
>
Understood. I was about to send v7 to remove this patch from the series, but too late. I'll test the current queue branch and provide update.
Best Regards,
Suravee
next prev parent reply other threads:[~2022-06-28 2:38 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-19 10:26 [PATCH v6 00/17] Introducing AMD x2AVIC and hybrid-AVIC modes Suravee Suthikulpanit
2022-05-19 10:26 ` [PATCH v6 01/17] x86/cpufeatures: Introduce x2AVIC CPUID bit Suravee Suthikulpanit
2022-06-24 16:08 ` Paolo Bonzini
2022-05-19 10:26 ` [PATCH v6 02/17] KVM: x86: lapic: Rename [GET/SET]_APIC_DEST_FIELD to [GET/SET]_XAPIC_DEST_FIELD Suravee Suthikulpanit
2022-06-24 16:08 ` Paolo Bonzini
2022-05-19 10:26 ` [PATCH v6 03/17] KVM: SVM: Detect X2APIC virtualization (x2AVIC) support Suravee Suthikulpanit
2022-05-19 10:26 ` [PATCH v6 04/17] KVM: SVM: Update max number of vCPUs supported for x2AVIC mode Suravee Suthikulpanit
2022-05-19 10:26 ` [PATCH v6 05/17] KVM: SVM: Update avic_kick_target_vcpus to support 32-bit APIC ID Suravee Suthikulpanit
2022-05-19 10:26 ` [PATCH v6 06/17] KVM: SVM: Do not support updating APIC ID when in x2APIC mode Suravee Suthikulpanit
2022-05-19 10:26 ` [PATCH v6 07/17] KVM: SVM: Adding support for configuring x2APIC MSRs interception Suravee Suthikulpanit
2022-05-19 10:27 ` [PATCH v6 08/17] KVM: x86: Deactivate APICv on vCPU with APIC disabled Suravee Suthikulpanit
2022-05-19 10:27 ` [PATCH v6 09/17] KVM: SVM: Refresh AVIC configuration when changing APIC mode Suravee Suthikulpanit
2022-05-19 10:27 ` [PATCH v6 10/17] KVM: x86: nSVM: always intercept x2apic msrs Suravee Suthikulpanit
2022-05-19 10:27 ` [PATCH v6 11/17] KVM: SVM: Introduce logic to (de)activate x2AVIC mode Suravee Suthikulpanit
2022-05-19 10:27 ` [PATCH v6 12/17] KVM: SVM: Do not throw warning when calling avic_vcpu_load on a running vcpu Suravee Suthikulpanit
2022-05-19 10:27 ` [PATCH v6 13/17] KVM: SVM: Introduce hybrid-AVIC mode Suravee Suthikulpanit
2022-05-19 10:27 ` [PATCH v6 14/17] KVM: x86: Warning APICv inconsistency only when vcpu APIC mode is valid Suravee Suthikulpanit
2022-05-19 10:27 ` [PATCH v6 15/17] KVM: SVM: Use target APIC ID to complete x2AVIC IRQs when possible Suravee Suthikulpanit
2022-06-24 16:41 ` Paolo Bonzini
2022-06-27 22:55 ` Maxim Levitsky
2022-06-28 2:35 ` Suthikulpanit, Suravee [this message]
2022-06-28 8:59 ` Maxim Levitsky
2022-06-28 12:36 ` Suthikulpanit, Suravee
2022-06-28 13:14 ` Maxim Levitsky
2022-05-19 10:27 ` [PATCH v6 16/17] KVM: SVM: Add AVIC doorbell tracepoint Suravee Suthikulpanit
2022-05-19 10:27 ` [PATCH v6 17/17] KVM: x86: nSVM: optimize svm_set_x2apic_msr_interception Suravee Suthikulpanit
2022-06-06 23:05 ` [PATCH v6 00/17] Introducing AMD x2AVIC and hybrid-AVIC modes Jim Mattson
2022-06-24 17:04 ` Paolo Bonzini
2022-06-28 13:20 ` Suthikulpanit, Suravee
2022-06-28 13:43 ` Maxim Levitsky
2022-06-28 16:34 ` Suthikulpanit, Suravee
2022-06-29 7:10 ` Maxim Levitsky
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=9f3ffe16-2516-d4ec-528e-6347ef884ad5@amd.com \
--to=suravee.suthikulpanit@amd.com \
--cc=jon.grimm@amd.com \
--cc=joro@8bytes.org \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mlevitsk@redhat.com \
--cc=pbonzini@redhat.com \
--cc=seanjc@google.com \
--cc=terry.bowman@amd.com \
--cc=wei.huang2@amd.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).