On 21/04/2015 16:30, Laszlo Ersek wrote: >> > - MemoryRegion tseg_blackhole; >> > + MemoryRegion tseg_blackhole, tseg_window; >> > PcPciInfo pci_info; >> > ram_addr_t below_4g_mem_size; >> > ram_addr_t above_4g_mem_size; >> > > Why is this necessary? If you disable the black hole overlay, the access > will go to the RAM. (Or can't that be done per-CPU?)
The reason to have two separate MemoryRegions is exactly to allow per-CPU access. tseg_blackhole is added on top of address_space_memory to hide TSEG; tseg_window is included in /machine/smram and TCG adds it to the private per-CPU address space when it enters system management mode. > I'm thinking, the last 1 / 2 / 8 megabytes should behave as RAM in all > of the following cases: > - no SMRAM programmed (tseg size = 0) > - SMRAM programmed (tseg size > 0), and it is open > - SMRAM programmed (tseg size > 0) and closed, but CPU in SMM Correct. However, you can have one CPU in SMM and another executing "normal" code. It would be a hole to allow that CPU to read (or worse, write) the TSEG or legacy SMRAM areas. > ... Another question, related to SMM (but not related to SMRAM): Paolo, > am I right to think that we'll be keying off at least two independent > things of SMM-or-not: one is access to SMRAM (tseg), for LockBox and SMM > driver purposes, the other is pflash access (with the MemTxAttrs thing), > for the varstore? Yes. Paolo