From: Jon Kohler <jon@nutanix.com>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Jon Kohler <jon@nutanix.com>, Babu Moger <babu.moger@amd.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"x86@kernel.org" <x86@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <seanjc@google.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
Yu-cheng Yu <yu-cheng.yu@intel.com>,
Fenghua Yu <fenghua.yu@intel.com>,
Tony Luck <tony.luck@intel.com>,
Petteri Aimonen <jpa@git.mail.kapsi.fi>,
Kan Liang <kan.liang@linux.intel.com>,
Uros Bizjak <ubizjak@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Mike Rapoport <rppt@kernel.org>,
Benjamin Thiel <b.thiel@posteo.de>,
Anshuman Khandual <anshuman.khandual@arm.com>,
Juergen Gross <jgross@suse.com>, Fan Yang <Fan_Yang@sjtu.edu.cn>,
Dave Jiang <dave.jiang@intel.com>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
Ricardo Neri <ricardo.neri-calderon@linux.intel.com>,
Arvind Sankar <nivedita@alum.mit.edu>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: Re: [PATCH v2] KVM: x86: use wrpkru directly in kvm_load_{guest|host}_xsave_state
Date: Tue, 11 May 2021 16:49:20 +0000 [thread overview]
Message-ID: <3BABBCC3-33EB-4BC4-9384-14746AFE2D1C@nutanix.com> (raw)
In-Reply-To: <ab09f739-89fa-901d-9ee3-27a6c674d9a0@intel.com>
> On May 11, 2021, at 12:45 PM, Dave Hansen <dave.hansen@intel.com> wrote:
>
> On 5/11/21 8:59 AM, Jon Kohler wrote:
>> diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
>> index b1099f2d9800..20f1fb8be7ef 100644
>> --- a/arch/x86/include/asm/pgtable.h
>> +++ b/arch/x86/include/asm/pgtable.h
>> @@ -151,7 +151,7 @@ static inline void write_pkru(u32 pkru)
>> fpregs_lock();
>> if (pk)
>> pk->pkru = pkru;
>> - __write_pkru(pkru);
>> + wrpkru(pkru);
>> fpregs_unlock();
>> }
>
> This removes the:
>
> if (pkru == rdpkru())
> return;
>
> optimization from a couple of write_pkru() users:
> arch_set_user_pkey_access() and copy_init_pkru_to_fpregs().
>
> Was that intentional? Those aren't the hottest paths in the kernel, but
> copy_init_pkru_to_fpregs() is used in signal handling and exeve().
That wasn’t intentional, I’ll take a look and send out a v3 pronto.
Thanks, Dave
next prev parent reply other threads:[~2021-05-11 16:51 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-11 15:59 [PATCH v2] KVM: x86: use wrpkru directly in kvm_load_{guest|host}_xsave_state Jon Kohler
2021-05-11 16:45 ` Dave Hansen
2021-05-11 16:49 ` Jon Kohler [this message]
2021-05-11 17:08 ` Paolo Bonzini
2021-05-11 17:10 ` Jon Kohler
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