On 21.04.2022 15:21, Roger Pau Monne wrote:
> Do not allow to write to RTE registers using io_apic_write and instead
> require changes to RTE to be performed using ioapic_write_entry.
Hmm, this doubles the number of MMIO access in affected code fragments.
> --- a/xen/arch/x86/include/asm/io_apic.h
> +++ b/xen/arch/x86/include/asm/io_apic.h
> @@ -161,22 +161,11 @@ static inline void __io_apic_write(unsigned int apic,
> unsigned int reg, unsigned
>
> static inline void io_apic_write(unsigned int apic, unsigned int reg,
> unsigned int value)
> {
> - if ( ioapic_reg_remapped(reg) )
> - return iommu_update_ire_from_apic(apic, reg, value);
> + /* RTE writes must use ioapic_write_entry. */
> + BUG_ON(reg >= 0x10);
> __io_apic_write(apic, reg, value);
> }
>
> -/*
> - * Re-write a value: to be used for read-modify-write
> - * cycles where the read already set up the index register.
> - */
> -static inline void io_apic_modify(unsigned int apic, unsigned int reg,
> unsigned int value)
> -{
> - if ( ioapic_reg_remapped(reg) )
> - return iommu_update_ire_from_apic(apic, reg, value);
> - *(IO_APIC_BASE(apic) + 4) = value;
> -}
While the last caller goes away, I don't think this strictly needs to
be dropped (but could just gain a BUG_ON() like you do a few lines up)?
Jan
