117 lines
3.3 KiB
ArmAsm
117 lines
3.3 KiB
ArmAsm
/* SPDX-License-Identifier: GPL-2.0
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*
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* Assembly level code for mshv_vtl VTL transition
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*
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* Copyright (c) 2025, Microsoft Corporation.
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*
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* Author:
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* Naman Jain <namjain@microsoft.com>
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*/
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#include <linux/linkage.h>
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#include <linux/static_call_types.h>
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#include <asm/asm.h>
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#include <asm/asm-offsets.h>
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#include <asm/frame.h>
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#include "mshv-asm-offsets.h"
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.text
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.section .noinstr.text, "ax"
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/*
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* void __mshv_vtl_return_call(struct mshv_vtl_cpu_context *vtl0)
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*
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* This function is used to context switch between different Virtual Trust Levels.
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* It is marked as 'noinstr' to prevent against instrumentation and debugging facilities.
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* NMIs aren't a problem because the NMI handler saves/restores CR2 specifically to guard
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* against #PFs in NMI context clobbering the guest state.
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*/
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SYM_FUNC_START(__mshv_vtl_return_call)
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/* Push callee save registers */
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pushq %rbp
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mov %rsp, %rbp
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pushq %r12
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pushq %r13
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pushq %r14
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pushq %r15
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pushq %rbx
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/* register switch to VTL0 clobbers all registers except rax/rcx */
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mov %_ASM_ARG1, %rax
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/* grab rbx/rbp/rsi/rdi/r8-r15 */
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mov MSHV_VTL_CPU_CONTEXT_rbx(%rax), %rbx
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mov MSHV_VTL_CPU_CONTEXT_rbp(%rax), %rbp
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mov MSHV_VTL_CPU_CONTEXT_rsi(%rax), %rsi
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mov MSHV_VTL_CPU_CONTEXT_rdi(%rax), %rdi
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mov MSHV_VTL_CPU_CONTEXT_r8(%rax), %r8
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mov MSHV_VTL_CPU_CONTEXT_r9(%rax), %r9
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mov MSHV_VTL_CPU_CONTEXT_r10(%rax), %r10
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mov MSHV_VTL_CPU_CONTEXT_r11(%rax), %r11
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mov MSHV_VTL_CPU_CONTEXT_r12(%rax), %r12
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mov MSHV_VTL_CPU_CONTEXT_r13(%rax), %r13
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mov MSHV_VTL_CPU_CONTEXT_r14(%rax), %r14
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mov MSHV_VTL_CPU_CONTEXT_r15(%rax), %r15
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mov MSHV_VTL_CPU_CONTEXT_cr2(%rax), %rdx
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mov %rdx, %cr2
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mov MSHV_VTL_CPU_CONTEXT_rdx(%rax), %rdx
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/* stash host registers on stack */
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pushq %rax
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pushq %rcx
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xor %ecx, %ecx
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/* make a hypercall to switch VTL */
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call STATIC_CALL_TRAMP_STR(__mshv_vtl_return_hypercall)
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/* stash guest registers on stack, restore saved host copies */
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pushq %rax
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pushq %rcx
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mov 16(%rsp), %rcx
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mov 24(%rsp), %rax
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mov %rdx, MSHV_VTL_CPU_CONTEXT_rdx(%rax)
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mov %cr2, %rdx
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mov %rdx, MSHV_VTL_CPU_CONTEXT_cr2(%rax)
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pop MSHV_VTL_CPU_CONTEXT_rcx(%rax)
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pop MSHV_VTL_CPU_CONTEXT_rax(%rax)
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add $16, %rsp
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/* save rbx/rbp/rsi/rdi/r8-r15 */
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mov %rbx, MSHV_VTL_CPU_CONTEXT_rbx(%rax)
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mov %rbp, MSHV_VTL_CPU_CONTEXT_rbp(%rax)
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mov %rsi, MSHV_VTL_CPU_CONTEXT_rsi(%rax)
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mov %rdi, MSHV_VTL_CPU_CONTEXT_rdi(%rax)
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mov %r8, MSHV_VTL_CPU_CONTEXT_r8(%rax)
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mov %r9, MSHV_VTL_CPU_CONTEXT_r9(%rax)
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mov %r10, MSHV_VTL_CPU_CONTEXT_r10(%rax)
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mov %r11, MSHV_VTL_CPU_CONTEXT_r11(%rax)
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mov %r12, MSHV_VTL_CPU_CONTEXT_r12(%rax)
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mov %r13, MSHV_VTL_CPU_CONTEXT_r13(%rax)
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mov %r14, MSHV_VTL_CPU_CONTEXT_r14(%rax)
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mov %r15, MSHV_VTL_CPU_CONTEXT_r15(%rax)
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/* pop callee-save registers r12-r15, rbx */
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pop %rbx
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pop %r15
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pop %r14
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pop %r13
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pop %r12
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pop %rbp
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RET
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SYM_FUNC_END(__mshv_vtl_return_call)
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/*
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* Make sure that static_call_key symbol: __SCK____mshv_vtl_return_hypercall is accessible here.
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* Below code is inspired from __ADDRESSABLE(sym) macro. Symbol name is kept simple, to avoid
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* naming it something like "__UNIQUE_ID_addressable___SCK____mshv_vtl_return_hypercall_662.0"
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* which would otherwise have been generated by the macro.
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*/
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.section .discard.addressable,"aw"
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.align 8
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.type mshv_vtl_return_sym, @object
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.size mshv_vtl_return_sym, 8
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mshv_vtl_return_sym:
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.quad __SCK____mshv_vtl_return_hypercall
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