On 08/08/2025 9:23 pm, Andrew Cooper wrote:
> diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
> index 270b93ed623e..e67a428e4362 100644
> --- a/xen/arch/x86/traps.c
> +++ b/xen/arch/x86/traps.c
> @@ -2181,6 +2240,94 @@ void asmlinkage check_ist_exit(const struct
> cpu_user_regs *regs, bool ist_exit)
> }
> #endif
>
> +void asmlinkage entry_from_pv(struct cpu_user_regs *regs)
> +{
> + /* Copy fred_ss.vector into entry_vector as IDT delivery would have
> done. */
> + regs->entry_vector = regs->fred_ss.vector;
> +
> + switch ( regs->fred_ss.type )
> + {
> + case X86_ET_EXT_INTR:
> + do_IRQ(regs);
> + break;
> +
> + case X86_ET_NMI:
> + do_nmi(regs);
> + break;
> +
> + case X86_ET_HW_EXC:
> + case X86_ET_SW_INT:
> + case X86_ET_PRIV_SW_EXC:
> + case X86_ET_SW_EXC:
> + goto fatal;
> +
> + default:
> + goto fatal;
> + }
> +
> + return;
> +
> + fatal:
> + fatal_trap(regs, false);
> +}
> +
> +void asmlinkage entry_from_xen(struct cpu_user_regs *regs)
> +{
> + /* Copy fred_ss.vector into entry_vector as IDT delivery would have
> done. */
> + regs->entry_vector = regs->fred_ss.vector;
> +
> + switch ( regs->fred_ss.type )
> + {
> + case X86_ET_EXT_INTR:
> + do_IRQ(regs);
> + break;
> +
> + case X86_ET_NMI:
> + do_nmi(regs);
> + break;
> +
> + case X86_ET_HW_EXC:
> + case X86_ET_SW_INT:
> + case X86_ET_PRIV_SW_EXC:
> + case X86_ET_SW_EXC:
> + switch ( regs->fred_ss.vector )
> + {
> + case X86_EXC_PF: do_page_fault(regs); break;
> + case X86_EXC_GP: do_general_protection(regs); break;
> + case X86_EXC_UD: do_invalid_op(regs); break;
> + case X86_EXC_NM: do_device_not_available(regs); break;
> + case X86_EXC_BP: do_int3(regs); break;
> + case X86_EXC_DB: do_debug(regs); break;
> + case X86_EXC_DF: do_double_fault(regs); break;
> +
> + case X86_EXC_DE:
> + case X86_EXC_OF:
> + case X86_EXC_BR:
> + case X86_EXC_NP:
> + case X86_EXC_SS:
> + case X86_EXC_MF:
> + case X86_EXC_AC:
> + case X86_EXC_XM:
> + do_trap(regs);
> + break;
> +
> + case X86_EXC_CP: do_entry_CP(regs); break;
> +
> + default:
> + goto fatal;
> + }
> + break;
> +
> + default:
> + goto fatal;
> + }
> +
> + return;
> +
> + fatal:
> + fatal_trap(regs, false);
> +}
Having started work on the PV support, I think this patch needs to
change somewhat.
I've split #DB and #PF to have separate IDT prologues, which in turns
gives us uniform handling of IRQ re-enabling for synchronous actions.
But, async still needs special handling.
I think we want something that looks more like:
switch ( regs->fred_ss.type )
{
case X86_ET_EXT_INTR: return do_IRQ(regs);
case X86_ET_NMI: return do_nmi(regs);
case X86_ET_HW_EXC:
if ( regs->fred_ss.vector == X86_EXC_MC )
return do_machine_check(regs);
break;
}
if ( regs->eflags & X86_EFLAGS_IF ) // From Xen only
local_irq_enable(); // From both
switch ( regs->fred_ss.type )
Either way, it's probably not worth focusing too much on how the C in
this patch looks for now.
~Andrew
