[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-devel] io_mem_notdirty and live migration

From: Hollis Blanchard
Subject: Re: [Qemu-devel] io_mem_notdirty and live migration
Date: Thu, 24 Mar 2016 12:30:01 -0700
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0

On 03/23/2016 09:53 AM, Paolo Bonzini wrote:
On 23/03/2016 17:47, Hollis Blanchard wrote:
Paolo, is it true that only TB-invalidating writes go through the
io_mem_notdirty path? I'm looking at the live migration code now, and it
seems like every memory write will go through that path when global
dirty memory logging is enabled.
When live migration is enabled, writes to clean memory (almost all of
them) will go through that path indeed.  Some writes to the framebuffer
will go through that path too.

It depends on

                         memory_region_get_ram_addr(section->mr) + xlat))

in tlb_set_page_with_attrs.

I'm guessing that when live migration starts (ram_save_setup), the TLB must be flushed so that new entries can be created with the TLB_NOTDIRTY flag. Otherwise, pre-migration entries without TLB_NOTDIRTY flag could live on, allowing the TBs to directly modify guest RAM without tracking, right?

I can't find anything underneath ram_save_setup() that does this, though. Am I just missing it?

Hollis Blanchard <address@hidden>
Mentor Graphics Emulation Division

reply via email to

[Prev in Thread] Current Thread [Next in Thread]