On 23/08/19 00:32, Kinney, Michael D wrote: > Paolo, > > It is my understanding that real HW hot plug uses the SDM defined > methods. Meaning the initial SMI is to 3000:8000 and they rebase > to TSEG in the first SMI. They must have chipset specific methods > to protect 3000:8000 from DMA.
It would be great if you could check. > Can we add a chipset feature to prevent DMA to 64KB range from > 0x30000-0x3FFFF and the UEFI Memory Map and ACPI content can be > updated so the Guest OS knows to not use that range for DMA? If real hardware does it at the chipset level, we will probably use Igor's suggestion of aliasing A-seg to 3000:0000. Before starting the new CPU, the SMI handler can prepare the SMBASE relocation trampoline at A000:8000 and the hot-plugged CPU will find it at 3000:8000 when it receives the initial SMI. Because this is backed by RAM at 0xA0000-0xAFFFF, DMA cannot access it and would still go through to RAM at 0x30000. Paolo -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#46306): https://edk2.groups.io/g/devel/message/46306 Mute This Topic: https://groups.io/mt/32979681/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
