linux-kernel - Re: [PATCH] kvm: x86: reduce rtc 0x70 access vm-exit time

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Message-ID: <ed3b4ef3-4dd5-7e82-9227-c80321821cb5@redhat.com>
Date:   Wed, 2 Aug 2017 10:50:09 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     peng.hao2@....com.cn
Cc:     rkrcmar@...hat.com, tglx@...utronix.de, mingo@...hat.com,
        hpa@...or.com, x86@...nel.org, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kvm: x86: reduce rtc 0x70 access vm-exit time

On 02/08/2017 10:45, peng.hao2@....com.cn wrote:
>>On 02/08/2017 17:24, Peng Hao wrote:
> coalesced MMIO is async and io port should be sync .  I don't need to
> coalese io port access.

Coalesced MMIO access is resolved on the next read from a coalesced MMIO
address or the next write to a non-coalescecd MMIO address.  So it would
work perfectly for port 0x70.  You would have to modify QEMU to split
the RTC I/O ports into two MemoryRegions.

Paolo