From: Erdem Aktas <[email protected]> Add code to boot a TDX test VM. Since TDX registers are inaccessible to KVM, the boot code loads the relevant values from memory into the registers before jumping to the guest code.
Reviewed-by: Binbin Wu <[email protected]> Signed-off-by: Erdem Aktas <[email protected]> Co-developed-by: Ackerley Tng <[email protected]> Signed-off-by: Ackerley Tng <[email protected]> Co-developed-by: Sagi Shahar <[email protected]> Signed-off-by: Sagi Shahar <[email protected]> Signed-off-by: Lisa Wang <[email protected]> --- tools/testing/selftests/kvm/Makefile.kvm | 1 + .../selftests/kvm/include/x86/tdx/td_boot.h | 22 ++++++-- tools/testing/selftests/kvm/lib/x86/tdx/td_boot.S | 61 ++++++++++++++++++++++ 3 files changed, 81 insertions(+), 3 deletions(-) diff --git a/tools/testing/selftests/kvm/Makefile.kvm b/tools/testing/selftests/kvm/Makefile.kvm index 397afebbb34b..645d9aac61db 100644 --- a/tools/testing/selftests/kvm/Makefile.kvm +++ b/tools/testing/selftests/kvm/Makefile.kvm @@ -32,6 +32,7 @@ LIBKVM_x86 += lib/x86/svm.c 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_arm64 += lib/arm64/gic.c LIBKVM_arm64 += lib/arm64/gic_v3.c diff --git a/tools/testing/selftests/kvm/include/x86/tdx/td_boot.h b/tools/testing/selftests/kvm/include/x86/tdx/td_boot.h index bf2282931d49..89cf6c3485be 100644 --- a/tools/testing/selftests/kvm/include/x86/tdx/td_boot.h +++ b/tools/testing/selftests/kvm/include/x86/tdx/td_boot.h @@ -2,9 +2,6 @@ #ifndef SELFTEST_TDX_TD_BOOT_H #define SELFTEST_TDX_TD_BOOT_H -#include <linux/compiler.h> -#include <linux/types.h> - /* * Layout for boot section (not to scale) * @@ -24,7 +21,19 @@ * | | * | | * |___________________________|____ 0x0_ffff_0000: TD_BOOT_PARAMETERS_GPA + * + * TD_BOOT_PARAMETERS_GPA is arbitrarily chosen to + * + * + be within the 4GB address space + * + provide enough contiguous memory for the struct td_boot_parameters such + * that there is one struct td_per_vcpu_parameters for KVM_MAX_VCPUS */ +#define TD_BOOT_PARAMETERS_GPA 0xffff0000 + +#if !defined(__ASSEMBLY__) && !defined(__ASSEMBLER__) + +#include <linux/compiler.h> +#include <linux/types.h> /* * The exact memory layout for LGDT or LIDT instructions. @@ -63,4 +72,11 @@ struct td_boot_parameters { struct td_per_vcpu_parameters per_vcpu[]; }; +void td_boot(void); +void td_boot_code_end(void); + +#define TD_BOOT_CODE_SIZE (td_boot_code_end - td_boot) + +#endif /* !defined(__ASSEMBLY__) && !defined(__ASSEMBLER__) */ + #endif /* SELFTEST_TDX_TD_BOOT_H */ diff --git a/tools/testing/selftests/kvm/lib/x86/tdx/td_boot.S b/tools/testing/selftests/kvm/lib/x86/tdx/td_boot.S new file mode 100644 index 000000000000..bca9a4c3d8f8 --- /dev/null +++ b/tools/testing/selftests/kvm/lib/x86/tdx/td_boot.S @@ -0,0 +1,61 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ + +#include "tdx/td_boot.h" +#include "tdx/td_boot_offsets.h" +#include "processor_asm.h" + +.code32 + +.globl td_boot +td_boot: + /* + * In this procedure, edi is used as a temporary register. + * Paging is turned off. + */ + cli + + movl $TD_BOOT_PARAMETERS_GPA, %ebx + + /* + * Find the address of struct td_per_vcpu_parameters for this + * vCPU based on esi (TDX spec: initialized with vCPU id). Put + * struct address into register for indirect addressing. + */ + movl $SIZEOF_TD_PER_VCPU_PARAMETERS, %eax + mul %esi + leal TD_BOOT_PARAMETERS_PER_VCPU(%ebx), %edi + addl %edi, %eax + + /* Setup stack. */ + movl TD_PER_VCPU_PARAMETERS_ESP_GVA(%eax), %esp + + /* Setup GDT. */ + leal TD_BOOT_PARAMETERS_GDT(%ebx), %edi + lgdt (%edi) + + /* Setup IDT. */ + leal TD_BOOT_PARAMETERS_IDT(%ebx), %edi + lidt (%edi) + + /* + * Set up control registers (There are no instructions to mov from + * memory to control registers, hence use edi as a scratch register). + */ + movl TD_BOOT_PARAMETERS_CR4(%ebx), %edi + movl %edi, %cr4 + movl TD_BOOT_PARAMETERS_CR3(%ebx), %edi + movl %edi, %cr3 + movl TD_BOOT_PARAMETERS_CR0(%ebx), %edi + movl %edi, %cr0 + + /* Switching to 64bit mode after ljmp and then jump to guest code */ + ljmp $(KERNEL_CS),$1f +1: + jmp *TD_PER_VCPU_PARAMETERS_GUEST_CODE(%eax) + +/* Leave marker so size of td_boot code can be computed. */ +.globl td_boot_code_end +td_boot_code_end: + +/* Disable executable stack. */ +.section .note.GNU-stack,"",%progbits -- 2.55.0.229.g6434b31f56-goog
