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. Signed-off-by: Erdem Aktas <[email protected]> Co-developed-by: Sagi Shahar <[email protected]> Signed-off-by: Sagi Shahar <[email protected]> Co-developed-by: Lisa Wang <[email protected]> Signed-off-by: Lisa Wang <[email protected]> --- tools/testing/selftests/kvm/Makefile.kvm | 1 + tools/testing/selftests/kvm/include/x86/tdx/tdx.h | 17 +++++++++++ tools/testing/selftests/kvm/lib/x86/tdx/tdx.S | 37 +++++++++++++++++++++++ 3 files changed, 55 insertions(+) diff --git a/tools/testing/selftests/kvm/Makefile.kvm b/tools/testing/selftests/kvm/Makefile.kvm index 645d9aac61db..28b33ed8c2e6 100644 --- a/tools/testing/selftests/kvm/Makefile.kvm +++ b/tools/testing/selftests/kvm/Makefile.kvm @@ -33,6 +33,7 @@ LIBKVM_x86 += lib/x86/tdx/tdx_util.c LIBKVM_x86 += lib/x86/ucall.c LIBKVM_x86 += lib/x86/vmx.c LIBKVM_x86 += lib/x86/tdx/td_boot.S +LIBKVM_x86 += lib/x86/tdx/tdx.S LIBKVM_arm64 += lib/arm64/gic.c LIBKVM_arm64 += lib/arm64/gic_v3.c 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 + +u64 __tdcall(u64 leaf, u64 r12, u64 r13, u64 r14, u64 r15); + +static inline u64 tdx_mmio_write(u64 address, u32 size, u64 data_in) +{ + return __tdcall(TDG_VP_VMCALL_VE_REQUEST_MMIO, size, + TDVMCALL_MMIO_WRITE, address, data_in); +} +#endif /* SELFTEST_KVM_TDX_TDX_H */ diff --git a/tools/testing/selftests/kvm/lib/x86/tdx/tdx.S b/tools/testing/selftests/kvm/lib/x86/tdx/tdx.S new file mode 100644 index 000000000000..dff48a3624a1 --- /dev/null +++ b/tools/testing/selftests/kvm/lib/x86/tdx/tdx.S @@ -0,0 +1,37 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ + +.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 */ + + mov %rdi, %r11 + mov %rsi, %r12 + mov %rdx, %r13 + mov %rcx, %r14 + mov %r8, %r15 + + /* TDCALL boilerplate */ + mov $0, %rax + mov $0xFC00, %rcx /* Expose R10-R15 */ + mov $0, %r10 + + /* tdcall instruction */ + .byte 0x66, 0x0f, 0x01, 0xcc + + /* Extract status */ + mov %r10, %rax + + pop %r15 + pop %r14 + pop %r13 + pop %r12 + ret -- 2.55.0.229.g6434b31f56-goog
