[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v4 7/7] x86/HVM: reduce scope of pfec in hvm_emulate_init_per_insn()
It needs calculating only in one out of three cases. Re-structure the code a little such that the variable truly gets calculated only when we don't get any insn bytes from elsewhere, and hence need to (try to) fetch them. Also OR in PFEC_insn_fetch right in the initializer. While in this mood, restrict addr's scope as well. Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx> --- v4: New. --- a/xen/arch/x86/hvm/emulate.c +++ b/xen/arch/x86/hvm/emulate.c @@ -2762,8 +2762,6 @@ void hvm_emulate_init_per_insn( unsigned int insn_bytes) { struct vcpu *curr = current; - unsigned int pfec = PFEC_page_present; - unsigned long addr; hvmemul_ctxt->ctxt.lma = hvm_long_mode_active(curr); @@ -2778,14 +2776,23 @@ void hvm_emulate_init_per_insn( hvmemul_ctxt->seg_reg[x86_seg_ss].db ? 32 : 16; } - if ( hvmemul_ctxt->seg_reg[x86_seg_ss].dpl == 3 ) - pfec |= PFEC_user_mode; - hvmemul_ctxt->insn_buf_eip = hvmemul_ctxt->ctxt.regs->rip; - if ( !insn_bytes ) + + if ( insn_bytes ) { + hvmemul_ctxt->insn_buf_bytes = insn_bytes; + memcpy(hvmemul_ctxt->insn_buf, insn_buf, insn_bytes); + } + else if ( !(hvmemul_ctxt->insn_buf_bytes = + hvm_get_insn_bytes(curr, hvmemul_ctxt->insn_buf)) ) + { + unsigned int pfec = PFEC_page_present | PFEC_insn_fetch; + unsigned long addr; + + if ( hvmemul_ctxt->seg_reg[x86_seg_ss].dpl == 3 ) + pfec |= PFEC_user_mode; + hvmemul_ctxt->insn_buf_bytes = - hvm_get_insn_bytes(curr, hvmemul_ctxt->insn_buf) ?: (hvm_virtual_to_linear_addr(x86_seg_cs, &hvmemul_ctxt->seg_reg[x86_seg_cs], hvmemul_ctxt->insn_buf_eip, @@ -2795,15 +2802,9 @@ void hvm_emulate_init_per_insn( &addr) && hvm_copy_from_guest_linear(hvmemul_ctxt->insn_buf, addr, sizeof(hvmemul_ctxt->insn_buf), - pfec | PFEC_insn_fetch, - NULL) == HVMTRANS_okay) ? + pfec, NULL) == HVMTRANS_okay) ? sizeof(hvmemul_ctxt->insn_buf) : 0; } - else - { - hvmemul_ctxt->insn_buf_bytes = insn_bytes; - memcpy(hvmemul_ctxt->insn_buf, insn_buf, insn_bytes); - } } void hvm_emulate_writeback( _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
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