Hi Paul, On Tue, May 22, 2018 at 07:41:51PM +1000, Paul Mackerras wrote: > On Mon, May 21, 2018 at 01:24:24PM +0800, wei.guo.simon@xxxxxxxxx wrote: > > From: Simon Guo <wei.guo.simon@xxxxxxxxx> > > > > This patch reimplements LOAD_VSX/STORE_VSX instruction MMIO emulation with > > analyse_intr() input. It utilizes VSX_FPCONV/VSX_SPLAT/SIGNEXT exported > > by analyse_instr() and handle accordingly. > > > > When emulating VSX store, the VSX reg will need to be flushed so that > > the right reg val can be retrieved before writing to IO MEM. > > When I tested this patch set with the MMIO emulation test program I > have, I got a host crash on the first test that used a VSX instruction > with a register number >= 32, that is, a VMX register. The crash was > that it hit the BUG() at line 1193 of arch/powerpc/kvm/powerpc.c. > > The reason it hit the BUG() is that vcpu->arch.io_gpr was 0xa3. > What's happening here is that analyse_instr gives a register numbers > in the range 32 - 63 for VSX instructions which access VMX registers. > When 35 is ORed with 0x80 (KVM_MMIO_REG_VSX) we get 0xa3. > > The old code didn't pass the high bit of the register number to > kvmppc_handle_vsx_load/store, but instead passed it via the > vcpu->arch.mmio_vsx_tx_sx_enabled field. With your patch set we still > set and use that field, so the patch below on top of your patches is > the quick fix. Ideally we would get rid of that field and just use > the high (0x20) bit of the register number instead, but that can be > cleaned up later. > > If you like, I will fold the patch below into this patch and push the > series to my kvm-ppc-next branch. > > Paul. Sorry my test missed this kind of cases. Please go ahead to fold the patch as you suggested. Thanks for point it out. If you like, I can do the clean up work. If I understand correctly, we need to expand io_gpr to u16 from u8 so that reg number can use 6 bits and leave room for other reg flag bits. BR, - Simon > --- > diff --git a/arch/powerpc/kvm/emulate_loadstore.c b/arch/powerpc/kvm/emulate_loadstore.c > index 0165fcd..afde788 100644 > --- a/arch/powerpc/kvm/emulate_loadstore.c > +++ b/arch/powerpc/kvm/emulate_loadstore.c > @@ -242,8 +242,8 @@ int kvmppc_emulate_loadstore(struct kvm_vcpu *vcpu) > } > > emulated = kvmppc_handle_vsx_load(run, vcpu, > - KVM_MMIO_REG_VSX|op.reg, io_size_each, > - 1, op.type & SIGNEXT); > + KVM_MMIO_REG_VSX | (op.reg & 0x1f), > + io_size_each, 1, op.type & SIGNEXT); > break; > } > #endif > @@ -363,7 +363,7 @@ int kvmppc_emulate_loadstore(struct kvm_vcpu *vcpu) > } > > emulated = kvmppc_handle_vsx_store(run, vcpu, > - op.reg, io_size_each, 1); > + op.reg & 0x1f, io_size_each, 1); > break; > } > #endif
