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Date: Tue, 2 Jun 2015 22:10:32 +0200
From: Aurelien Jarno <aurelien@aurel32.net>
Message-ID: <20150602201032.GA5379@aurel32.net>
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Subject: Re: [Qemu-devel] [PATCH RFC 3/5] softmmu: add a
	tlb_vaddr_to_host_fill function
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To: qemu-devel@nongnu.org
Cc: Peter Maydell <peter.maydell@linaro.org>, Alexander Graf <agraf@suse.de>, Yongbok Kim <yongbok.kim@imgtec.com>, Paolo Bonzini <pbonzini@redhat.com>, Leon Alrae <leon.alrae@imgtec.com>, Andreas =?iso-8859-15?Q?F=E4rber?= <afaerber@suse.de>, Richard Henderson <rth@twiddle.net>

On 2015-06-02 13:26, Aurelien Jarno wrote:
> The softmmu code already provides a tlb_vaddr_to_host function, which
> returns the host address corresponding to a guest virtual address,
> *if it is already in the QEMU MMU TLB*.
> 
> This patch is an attempt to have a function which try to fill the TLB
> entry if it is not already in the QEMU MMU TLB, possibly trigger a guest
> fault. It can be used directly in helpers. For that it creates a common
> function with a boolean to tell if the TLB needs to be filled or not. If
> yes, it causes tlb_fill, which might trigger an exception or succeed in
> which case the tlbentry pointer need to be reloaded.
> 
> I also had to change the MMIO test part. It seems that in write mode
> some TLB entries are filled with TLB_NOTDIRTY. They are caught by the
> MMIO test and a NULL pointer is returned instead. I am not sure of my
> change, but I guess the current softmmu code has the same issue.

It looks like we have to go through the MMIO functions to get the
TLB_NOTDIRTY bit cleaned correctly. This is something we don't want for
probe_write, so we definitely want two different functions.

-- 
Aurelien Jarno                          GPG: 4096R/1DDD8C9B
aurelien@aurel32.net                 http://www.aurel32.net