Hi Marc, Thanks for your help. I studied the kvm_handle_guest_abort() handler, and basically know the reason for "return 0". But I still cannot solve the mapping problem.
I want to find a function or APIs, whose input parameters are (1) region base IPA and size (2) mapped PA in Host (if IPA=PA, it could be better) (3) R/W/X attributes. Then, when I call the func(IPA start, IPA end, PA start, attr), I can get the map. Where should I follow? Should I follow the "translation fault path" again? Or create the mapping function by myself? Sincerely, Wang Marc Zyngier <[email protected]> 于2021年10月17日周日 上午5:19写道： > On Sat, 16 Oct 2021 13:21:01 +0100, > Chenxu Wang <[email protected]> wrote: > > > > Hi all, > > > > I am facing two problems with the Stage-2 translation in KVM. > > > > (1) > > I reserve a memory region (e.g., 0xa000_0000 ~ 0xa020_0000) from DRAM > space > > of HostOS, and fill it with some values. Then ask a GuestVM to access > this > > region. > > > > void __iomem *region=ioremap(0xa0000000, 0x1000); > > uint32_t val=ioread32(region); > > > > But I get value 0, which is not the expected value. > > It is the expected behaviour. > > > I guess the reason is that the Stage-2 translation of the GuestVM does > not > > map the reserved region, but it should return a translation fault, rather > > than 0. So I feel confused, could you provide some helpful explanation? > > Why should the guest see a translation fault? After all, the whole > point of KVM is to transparently handle the translation fault and map > a page on demand. > > > (2) > > I consider mapping a region with the Stage-2 translation. I find that KVM > > create the stage-2 table with kvm_alloc_stage2_pgd(). But I could not > find > > a function that can "arbitrarily add a stage-2 mapping to the physical > > address in HostOS" when the VM is activated. > > > > Could you provide such functions? > > Follow the translation fault path in KVM, and you will find what you > are asking for. > > M. > > -- > Without deviation from the norm, progress is not possible. >
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