From: Reinette Chatre <reinette.chatre@intel.com>
To: isaku.yamahata@intel.com, pbonzini@redhat.com,
erdemaktas@google.com, vkuznets@redhat.com, seanjc@google.com,
vannapurve@google.com, jmattson@google.com, mlevitsk@redhat.com,
xiaoyao.li@intel.com, chao.gao@intel.com,
rick.p.edgecombe@intel.com
Cc: reinette.chatre@intel.com, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: [PATCH V5 1/4] KVM: x86: hyper-v: Calculate APIC bus frequency for Hyper-V
Date: Thu, 25 Apr 2024 15:06:59 -0700 [thread overview]
Message-ID: <76a659d0898e87ebd73ee7c922f984a87a6ab370.1714081726.git.reinette.chatre@intel.com> (raw)
In-Reply-To: <cover.1714081725.git.reinette.chatre@intel.com>
From: Isaku Yamahata <isaku.yamahata@intel.com>
Remove APIC_BUS_FREQUENCY and calculate it based on nanoseconds per APIC
bus cycle. APIC_BUS_FREQUENCY is used only for HV_X64_MSR_APIC_FREQUENCY.
The MSR is not frequently read, calculate it every time.
There are two constants related to the APIC bus frequency:
APIC_BUS_FREQUENCY and APIC_BUS_CYCLE_NS.
Only one value is required because one can be calculated from the other:
APIC_BUS_CYCLES_NS = 1000 * 1000 * 1000 / APIC_BUS_FREQUENCY.
Remove APIC_BUS_FREQUENCY and instead calculate it when needed.
This prepares for support of configurable APIC bus frequency by
requiring to change only a single variable.
Suggested-by: Maxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
Reviewed-by: Maxim Levitsky <maximlevitsky@gmail.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
[reinette: rework changelog]
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
---
Changes v5:
- Add Rick's Reviewed-by tag.
Changes v4:
- Modify subject to match custom: "KVM: x86/hyperv:" ->
"KVM: x86: hyper-v:" and use standard capitalization for Hyper-V
("hyper-v" -> "Hyper-V").
- Rework changelog to remove pronouns ("we").
- Change logic in commit log: "APIC bus cycles per NS" -> "nanoseconds
per APIC bus cycle".
- Fix typos. (Maxim and Xiaoyao)
- Add Maxim and Xiaoyao's Reviewed-by tags.
- Add Maxim's "Suggested-by".
Changes v3:
- Newly added according to Maxim Levitsky suggestion.
arch/x86/kvm/hyperv.c | 2 +-
arch/x86/kvm/lapic.h | 1 -
2 files changed, 1 insertion(+), 2 deletions(-)
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 8a47f8541eab..1030701db967 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -1737,7 +1737,7 @@ static int kvm_hv_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata,
data = (u64)vcpu->arch.virtual_tsc_khz * 1000;
break;
case HV_X64_MSR_APIC_FREQUENCY:
- data = APIC_BUS_FREQUENCY;
+ data = div64_u64(1000000000ULL, APIC_BUS_CYCLE_NS);
break;
default:
kvm_pr_unimpl_rdmsr(vcpu, msr);
diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index 0a0ea4b5dd8c..a20cb006b6c8 100644
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -17,7 +17,6 @@
#define APIC_DEST_MASK 0x800
#define APIC_BUS_CYCLE_NS 1
-#define APIC_BUS_FREQUENCY (1000000000ULL / APIC_BUS_CYCLE_NS)
#define APIC_BROADCAST 0xFF
#define X2APIC_BROADCAST 0xFFFFFFFFul
--
2.34.1
next prev parent reply other threads:[~2024-04-25 22:07 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-25 22:06 [PATCH V5 0/4] KVM: x86: Make bus clock frequency for vAPIC timer configurable Reinette Chatre
2024-04-25 22:06 ` Reinette Chatre [this message]
2024-04-25 22:07 ` [PATCH V5 2/4] KVM: x86: Make nsec per APIC bus cycle a VM variable Reinette Chatre
2024-04-29 4:23 ` Xiaoyao Li
2024-04-25 22:07 ` [PATCH V5 3/4] KVM: x86: Add a capability to configure bus frequency for APIC timer Reinette Chatre
2024-04-28 6:24 ` Yuan Yao
2024-04-29 5:28 ` Xiaoyao Li
2024-04-25 22:07 ` [PATCH V5 4/4] KVM: selftests: Add test for configure of x86 APIC bus frequency Reinette Chatre
2024-04-26 23:06 ` Chen, Zide
2024-04-26 23:26 ` Reinette Chatre
2024-04-27 5:38 ` Chen, Zide
2024-04-29 15:23 ` Reinette Chatre
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=76a659d0898e87ebd73ee7c922f984a87a6ab370.1714081726.git.reinette.chatre@intel.com \
--to=reinette.chatre@intel.com \
--cc=chao.gao@intel.com \
--cc=erdemaktas@google.com \
--cc=isaku.yamahata@intel.com \
--cc=jmattson@google.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mlevitsk@redhat.com \
--cc=pbonzini@redhat.com \
--cc=rick.p.edgecombe@intel.com \
--cc=seanjc@google.com \
--cc=vannapurve@google.com \
--cc=vkuznets@redhat.com \
--cc=xiaoyao.li@intel.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.