On 09/20/19 10:28, Igor Mammedov wrote: > On Thu, 19 Sep 2019 19:02:07 +0200 > "Laszlo Ersek" <ler...@redhat.com> wrote: > >> Hi Igor, >> >> (+Brijesh) >> >> long-ish pondering ahead, with a question at the end. > [...] > >> Finally: can you please remind me why we lock down 128KB (32 pages) at >> 0x3_0000, and not just half of that? What do we need the range at >> [0x4_0000..0x4_FFFF] for? > > > If I recall correctly, CPU consumes 64K of save/restore area. > The rest 64K are temporary RAM for using in SMI relocation handler, > if it's possible to get away without it then we can drop it and > lock only 64K required for CPU state. It won't help with SEV > conflict though as it's in the first 64K.
OK. Let's go with 128KB for now. Shrinking the area is always easier than growing it. > On QEMU side, we can drop black-hole approach and allocate > dedicated SMRAM region, which explicitly gets mapped into > RAM address space and after SMI hanlder initialization, gets > unmapped (locked). So that SMRAM would be accessible only > from SMM context. That way RAM at 0x30000 could be used as > normal when SMRAM is unmapped. I prefer the black-hole approach, introduced in your current patch series, if it can work. Way less opportunity for confusion. I've started work on the counterpart OVMF patches; I'll report back. Thanks Laszlo -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#47712): https://edk2.groups.io/g/devel/message/47712 Mute This Topic: https://groups.io/mt/34201782/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
