On Mon, Mar 18, 2024 at 04:16:56PM -0700, Isaku Yamahata <isaku.yamahata@xxxxxxxxx> wrote: > On Mon, Mar 18, 2024 at 05:43:33PM +0000, > "Edgecombe, Rick P" <rick.p.edgecombe@xxxxxxxxx> wrote: > > > On Mon, 2024-03-18 at 10:12 -0700, Isaku Yamahata wrote: > > > I categorize as follows. Unless otherwise, I'll update this series. > > > > > > - dirty log check > > > As we will drop this ptach, we'll have no call site. > > > > > > - KVM_BUG_ON() in main.c > > > We should drop them because their logic isn't complex. > > What about "KVM: TDX: Add methods to ignore guest instruction > > emulation"? Is it cleanly blocked somehow? > > KVM fault handler, kvm_mmu_page_fault(), is the caller into the emulation, > It should skip the emulation. > > As the second guard, x86_emulate_instruction(), calls > check_emulate_instruction() callback to check if the emulation can/should be > done. TDX callback can return it as X86EMUL_UNHANDLEABLE. Then, the flow goes > to user space as error. I'll update the vt_check_emulate_instruction(). Oops. It was wrong. It should be X86EMUL_RETRY_INSTR. RETRY_INSTR means, let vcpu execute the intrusion again, UNHANDLEABLE means, emulator can't emulate, inject exception or give up with KVM_EXIT_INTERNAL_ERROR. For TDX, we'd like to inject #VE to the guest so that the guest #VE handler can issue TDG.VP.VMCALL<MMIO>. The default non-present sept value has #VE suppress bit set. As first step, EPT violation occurs. then KVM sets up mmio_spte with #VE suppress bit cleared. Then X86EMUL_RETRY_INSTR tells kvm to resume vcpu to inject #VE. -- Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
