On Mon, Apr 30, 2018 at 10:13 PM, Andrew Cooper <andrew.coop...@citrix.com> wrote:
> On 29/04/18 11:11, Minjun Hong wrote: > > Hi. > > I'm looking for a point where address translation (guest virtual > > address to machine address) occurs in Xen. > > Of course, I mean when TLB miss has occured. > > This question makes me wonder whether you are more familiar with PowerPC > than x86. In x86, the TLB is automatically maintained by hardware, and > new entries will be populated as necessary. All pagetable related > errors result in a pagefault exception, which Xen handles. > > > I'm using a PV guest and I've found 'guest_walk_tables()' function in > > "xen/arch/x86/mm/guest_walk.c". > > However, in the comment of the function, it says "Walk the guest > > pagetables, after the manner of a hardware walker". > > I'm confused because I'm not sure if the function is called after the > > 'hardware page table walker'. > > "after the manner" is an uncommon phrase in English, which AFAICT > derives from Latin originally. It means "in the style of", "in the same > way as", etc. > > guest_walk_tables() is a function which tries to match the behaviour of > the hardware pagewalker. However, it is only used for cases where we > can't use regular hardware support, such as emulation of instructions. > > ~Andrew > Thank you, Andrew. Your answer is very helpful for me. It appears that there is no code to be executed when address translations of the guest occurs in Xen. Frankly, I was expecting there may be an address translation when accessing guest memory, and I wanted to find the code used in Xen at that time. Is there any code I can use for this purpose in Xen? No matter how I look, I could not find it in Xen with my background knowledge right now. So that I need your help.
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