2017-11-29 23:12:10

by Eduardo Habkost

[permalink] [raw]
Subject: Re: [PATCH] KVM: x86: inject exceptions produced by x86_decode_insn

On Wed, Nov 29, 2017 at 11:47:14PM +0100, Paolo Bonzini wrote:
> On 29/11/2017 19:42, Eduardo Habkost wrote:
> > The reproducer (not a full test case) is quite simple, see patch below.
>
> Great, thanks. I assume that the patch doesn't fix it?!?

I was so convinced that it was impossible for the patch to fix
the problem, that I forgot to test it. :)

I will test it tomorrow and let you know.


>
> Paolo
>
> > Now, I've noticed something interesting when running the
> > reproducer:
> >
> > If the test_fetch_failure() call happens before we touch
> > pci-testdev through *mem (like in the patch below), we get an
> > emulation failure like the one Yanan saw:
> >
> > $ /usr/bin/qemu-system-x86_64 -nodefaults -device pc-testdev -device isa-debug-exit,iobase=0xf4,iosize=0x4 -vnc none -serial stdio -device pci-testdev -machine accel=kvm -kernel ./x86/emulator.flat # -initrd /tmp/tmp.RCPjppRp8i
> > enabling apic
> > paging enabled
> > cr0 = 80010011
> > cr3 = 45e000
> > cr4 = 20
> > KVM internal error. Suberror: 1
> > emulation failure
> > RAX=0000000000000000 RBX=0000000000000000 RCX=0000000000000000 RDX=0000000000000000
> > RSI=0000000000000000 RDI=0000000000000000 RBP=0000000000000000 RSP=0000000000000000
> > R8 =0000000000000000 R9 =0000000000000000 R10=0000000000000000 R11=0000000000000000
> > R12=0000000000000000 R13=0000000000000000 R14=0000000000000000 R15=0000000000000000
> > RIP=ffffffffffffc08a RFL=00010002 [-------] CPL=0 II=0 A20=1 SMM=0 HLT=0
> > ES =0010 0000000000000000 ffffffff 00c09300 DPL=0 DS [-WA]
> > CS =0008 0000000000000000 ffffffff 00a09b00 DPL=0 CS64 [-RA]
> > SS =0010 0000000000000000 ffffffff 00c09300 DPL=0 DS [-WA]
> > DS =0010 0000000000000000 ffffffff 00c09300 DPL=0 DS [-WA]
> > FS =0010 0000000000000000 ffffffff 00c09300 DPL=0 DS [-WA]
> > GS =0010 0000000000454d60 ffffffff 00c09300 DPL=0 DS [-WA]
> > LDT=0000 0000000000000000 0000ffff 00008200 DPL=0 LDT
> > TR =0080 000000000041148a 0000ffff 00008b00 DPL=0 TSS64-busy
> > GDT= 000000000041100a 0000047f
> > IDT= 0000000000000000 00000fff
> > CR0=80010011 CR2=ffffffffffffc08a CR3=000000000045e000 CR4=00000020
> > DR0=0000000000000000 DR1=0000000000000000 DR2=0000000000000000 DR3=0000000000000000
> > DR6=00000000ffff0ff0 DR7=0000000000000400
> > EFER=0000000000000500
> > Code=?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? <??> ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ??
>

--
Eduardo

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