On 07/09/2012 12:02 PM, Xiao Guangrong wrote:
> After commit f78146b0f9230765c6315b2e14f56112513389ad:
>
> KVM: Fix page-crossing MMIO
>
> MMIO that are split across a page boundary are currently broken - the
> code does not expect to be aborted by the exit to userspace for the
> first MMIO fragment.
>
> This patch fixes the problem by generalizing the current code for handling
> 16-byte MMIOs to handle a number of "fragments", and changes the MMIO
> code to create those fragments.
>
> Signed-off-by: Avi Kivity <avi@xxxxxxxxxx>
> Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
>
> Multiple MMIO reads can be merged into mmio_fragments, the read buffer is not
> needed anymore
>
> Signed-off-by: Xiao Guangrong <xiaoguangrong@xxxxxxxxxxxxxxxxxx>
> ---
> arch/x86/include/asm/kvm_emulate.h | 1 -
> arch/x86/kvm/emulate.c | 43 ++++-------------------------------
> arch/x86/kvm/x86.c | 2 -
> 3 files changed, 5 insertions(+), 41 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
> index 1ac46c22..339d7c6 100644
> --- a/arch/x86/include/asm/kvm_emulate.h
> +++ b/arch/x86/include/asm/kvm_emulate.h
> @@ -286,7 +286,6 @@ struct x86_emulate_ctxt {
> struct operand *memopp;
> struct fetch_cache fetch;
> struct read_cache io_read;
> - struct read_cache mem_read;
> };
>
Suppose we have a RMW instruction. On the first entry to
x86_emulate_insn() we'll drop to userspace and perform the read, and the
seconds we'll read from the cache and complete the write.
Without the read cache this cannot work.
kvm-unit-tests.git has a test for xchg to mmio. Does it still work?
I agree this code has to go, but it needs to be replaced by something.
Maybe a .valid flag in struct operand.
--
error compiling committee.c: too many arguments to function
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