Thanks James's explanation. Hi Christoffer, On 2017/5/9 22:28, James Morse wrote: > Hi Christoffer, > > On 08/05/17 18:54, Christoffer Dall wrote: >> On Mon, May 08, 2017 at 06:28:02PM +0100, James Morse wrote: >> I must admit I am losing track of exactly what this proposed API was >> supposed to do. > > There are two, and we keep jumping between them! > This is about two notification methods APEI has for arm64, 'SEA' and 'SEI'. > > SEA is synchronous and looks like a data abort. Qemu/kvmtool can inject these > today using the KVM_GET/SET_ONE_REG API whenever it wants to. > > SEI uses SError, is asynchronous and can be masked. In addition these need to be > consumed/synchronised by the ESB instruction, even when executed by a guest. > Hardware has the necessary bits to drive all this, we need to expose an API to > drive it. > > (I try to spell them out each time so I don't confuse SEI with something > synchronous!) > > > This patch was about SEA. I think you've answered our question: we are talking about the SEA(synchronous data abort) injection two methods: (1)change vcpu registers in the Qemu/kvmtools and using the KVM_GET/SET_ONE_REG API to set. (2)using existed in-kernel API "kvm_inject_dabt" to inject through IOCTL command from Qemu. > >> However, if it's a question about setting up VCPU registers to a certain >> state and potentially modifying memory, then I think experience has >> shown us (psci) that emulating something in the kernel that userspace >> can have fine-grained control over is a bad idea, and should be left to >> userspace using as generic APIs as possible. >> >> Furthermore, if I understand what injecting a SEA requires, it is very >> similar to resetting the CPU and loading data into guest memory, which >> QEMU already does today, and there is no reason to introduce additional >> APIs if it can be done using KVM_GET/SET_ONE_REG ioctls. > > > Thanks, > > James > > . >
