On Wed, Jul 22, 2026 at 11:13:25PM +0000, Lisa Wang wrote: > From: Erdem Aktas <[email protected]> > > Implement the tdx_mmio_write() to allow TDX VMs to request MMIO > emulation. > > Follow the Intel Guest-Hypervisor Communication Interface (GHCI) spec > to the minimum extent that a spec-abiding TDX module will pass the > request to KVM. Skip implementing the #VE handler as described in the > GHCI spec to reduce selftests dependency. > > To perform emulated I/O, VMs use the TDG.VP.VMCALL instruction to > request MMIO. >
[ ... ] > diff --git a/tools/testing/selftests/kvm/include/x86/tdx/tdx.h > b/tools/testing/selftests/kvm/include/x86/tdx/tdx.h > new file mode 100644 > index 000000000000..6355a30bb47f > --- /dev/null > +++ b/tools/testing/selftests/kvm/include/x86/tdx/tdx.h > @@ -0,0 +1,17 @@ > +/* SPDX-License-Identifier: GPL-2.0-only */ > +#ifndef SELFTEST_KVM_TDX_TDX_H > +#define SELFTEST_KVM_TDX_TDX_H > + > +#include <linux/types.h> > + > +#define TDG_VP_VMCALL_VE_REQUEST_MMIO 48 > +#define TDVMCALL_MMIO_WRITE 1 The indentation in these two lines is off. > + > +u64 __tdcall(u64 leaf, u64 r12, u64 r13, u64 r14, u64 r15); As Xiaoyao already pointed out, this function name is misleading. This is a TDG.VP.VMCALL (or a TDVMCALL), and r11 is a subfunction (the guest kernel simply calls it "fn"). > + > +.globl __tdcall > +/* > + * u64 __tdcall(u64 leaf, u64 r12, u64 r13, u64 r14, u64 r15) > + */ > +__tdcall: > + push %r12 > + push %r13 > + push %r14 > + push %r15 > + > + /* Map C ABI fast arguments to TDX GHCI payload registers */ > + /* RDI=leaf, RSI=r12, RDX=r13, RCX=r14, R8=r15 */ [ ... ] > + > + pop %r15 > + pop %r14 > + pop %r13 > + pop %r12 > + ret This is probably more of a nit... td_boot.S has: .section .note.GNU-stack,"",%progbits ...to disable executable stack. > > -- > 2.55.0.229.g6434b31f56-goog > >
