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From:   Thomas Gleixner <tglx@linutronix.de>
To:     Brian Gerst <brgerst@gmail.com>,
        Sean Christopherson <sean.j.christopherson@intel.com>
Cc:     Paolo Bonzini <pbonzini@redhat.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        kvm list <kvm@vger.kernel.org>,
        the arch/x86 maintainers <x86@kernel.org>,
        Dave Hansen <dave.hansen@intel.com>,
        Chang Seok Bae <chang.seok.bae@intel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Sasha Levin <sashal@kernel.org>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        Andy Lutomirski <luto@kernel.org>
Subject: Re: [PATCH v2] x86/entry/64: Do not use RDPID in paranoid entry to accomodate KVM
In-Reply-To: <CAMzpN2h79bi5dd7PxjY45xYy71UdYomKa1t2gNxLtRpDkMs+Lw@mail.gmail.com>
References: <20200821105229.18938-1-pbonzini@redhat.com> <20200821142152.GA6330@sjchrist-ice> <CAMzpN2h79bi5dd7PxjY45xYy71UdYomKa1t2gNxLtRpDkMs+Lw@mail.gmail.com>
Date:   Tue, 25 Aug 2020 12:44:29 +0200
Message-ID: <874kor57jm.fsf@nanos.tec.linutronix.de>
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On Fri, Aug 21 2020 at 11:35, Brian Gerst wrote:
> On Fri, Aug 21, 2020 at 10:22 AM Sean Christopherson
>> >  .macro GET_PERCPU_BASE reg:req
>> > -     ALTERNATIVE \
>> > -             "LOAD_CPU_AND_NODE_SEG_LIMIT \reg", \
>> > -             "RDPID  \reg", \
>>
>> This was the only user of the RDPID macro, I assume we want to yank that out
>> as well?
>
> No.  That one should be kept until the minimum binutils version is
> raised to one that supports the RDPID opcode.

The macro is unused and nothing in the kernel can use RDPID as we just
established.

Thanks,

        tglx