Nadav Amit <[email protected]> writes: > 32-bit operations are zero extended in 64-bit mode. Currently, the code does > not handle them correctly and keeps the high bits. In 16-bit mode, the high > 32-bits are kept intact. > > In addition, although it is not well-documented, when address override prefix
It would be helpful to have a pointer in the SDM especially for cases that are not well-documented. > is used with REP-string instruction, RCX high half is zeroed even if ECX was > zero on the first iteration (as if an assignment was performed to ECX). > > Signed-off-by: Nadav Amit <[email protected]> > --- > arch/x86/kvm/emulate.c | 38 +++++++++++++++++++++++--------------- > 1 file changed, 23 insertions(+), 15 deletions(-) > > diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c > index 743e8e3..6833b41 100644 > --- a/arch/x86/kvm/emulate.c > +++ b/arch/x86/kvm/emulate.c > @@ -434,9 +434,21 @@ static int emulator_check_intercept(struct > x86_emulate_ctxt *ctxt, > return ctxt->ops->intercept(ctxt, &info, stage); > } > > -static void assign_masked(ulong *dest, ulong src, ulong mask) > +static void assign_masked(ulong *dest, ulong src, int bytes) > { > - *dest = (*dest & ~mask) | (src & mask); > + switch (bytes) { > + case 2: > + *dest = (u16)src | (*dest & ~0xfffful); > + break; > + case 4: > + *dest = (u32)src; > + break; > + case 8: > + *dest = src; > + break; > + default: > + BUG(); IIRC, Paolo mentioned that a WARN() is preferable. But I see a lot other places where BUG() is called, maybe, he can confirm. > + } > } > > static inline unsigned long ad_mask(struct x86_emulate_ctxt *ctxt) > @@ -476,26 +488,20 @@ register_address(struct x86_emulate_ctxt *ctxt, > unsigned long reg) > return address_mask(ctxt, reg); > } > > -static void masked_increment(ulong *reg, ulong mask, int inc) > +static void masked_increment(ulong *reg, int size, int inc) > { > - assign_masked(reg, *reg + inc, mask); > + assign_masked(reg, *reg + inc, size); > } > > static inline void > register_address_increment(struct x86_emulate_ctxt *ctxt, unsigned long > *reg, int inc) > { > - ulong mask; > - > - if (ctxt->ad_bytes == sizeof(unsigned long)) > - mask = ~0UL; > - else > - mask = ad_mask(ctxt); > - masked_increment(reg, mask, inc); > + masked_increment(reg, ctxt->ad_bytes, inc); > } > > static void rsp_increment(struct x86_emulate_ctxt *ctxt, int inc) > { > - masked_increment(reg_rmw(ctxt, VCPU_REGS_RSP), stack_mask(ctxt), inc); > + masked_increment(reg_rmw(ctxt, VCPU_REGS_RSP), stack_size(ctxt), inc); > } > > static inline void jmp_rel(struct x86_emulate_ctxt *ctxt, int rel) > @@ -1712,17 +1718,17 @@ static int em_enter(struct x86_emulate_ctxt *ctxt) > if (rc != X86EMUL_CONTINUE) > return rc; > assign_masked(reg_rmw(ctxt, VCPU_REGS_RBP), reg_read(ctxt, > VCPU_REGS_RSP), > - stack_mask(ctxt)); > + stack_size(ctxt)); > assign_masked(reg_rmw(ctxt, VCPU_REGS_RSP), > reg_read(ctxt, VCPU_REGS_RSP) - frame_size, > - stack_mask(ctxt)); > + stack_size(ctxt)); > return X86EMUL_CONTINUE; > } > > static int em_leave(struct x86_emulate_ctxt *ctxt) > { > assign_masked(reg_rmw(ctxt, VCPU_REGS_RSP), reg_read(ctxt, > VCPU_REGS_RBP), > - stack_mask(ctxt)); > + stack_size(ctxt)); > return emulate_pop(ctxt, reg_rmw(ctxt, VCPU_REGS_RBP), ctxt->op_bytes); > } > > @@ -4570,6 +4576,8 @@ int x86_emulate_insn(struct x86_emulate_ctxt *ctxt) > if (ctxt->rep_prefix && (ctxt->d & String)) { > /* All REP prefixes have the same first termination condition */ > if (address_mask(ctxt, reg_read(ctxt, VCPU_REGS_RCX)) == 0) { > + assign_masked(reg_write(ctxt, VCPU_REGS_RCX), 0, > + ctxt->ad_bytes); > ctxt->eip = ctxt->_eip; > goto done; > } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
