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330 lines
7.9 KiB
330 lines
7.9 KiB
/* SPDX-License-Identifier: GPL-2.0 */ |
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#include <linux/linkage.h> |
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#include <asm/asm.h> |
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#include <asm/bitsperlong.h> |
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#include <asm/kvm_vcpu_regs.h> |
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#include <asm/nospec-branch.h> |
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#include <asm/segment.h> |
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#define WORD_SIZE (BITS_PER_LONG / 8) |
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#define VCPU_RAX __VCPU_REGS_RAX * WORD_SIZE |
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#define VCPU_RCX __VCPU_REGS_RCX * WORD_SIZE |
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#define VCPU_RDX __VCPU_REGS_RDX * WORD_SIZE |
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#define VCPU_RBX __VCPU_REGS_RBX * WORD_SIZE |
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/* Intentionally omit RSP as it's context switched by hardware */ |
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#define VCPU_RBP __VCPU_REGS_RBP * WORD_SIZE |
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#define VCPU_RSI __VCPU_REGS_RSI * WORD_SIZE |
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#define VCPU_RDI __VCPU_REGS_RDI * WORD_SIZE |
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#ifdef CONFIG_X86_64 |
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#define VCPU_R8 __VCPU_REGS_R8 * WORD_SIZE |
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#define VCPU_R9 __VCPU_REGS_R9 * WORD_SIZE |
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#define VCPU_R10 __VCPU_REGS_R10 * WORD_SIZE |
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#define VCPU_R11 __VCPU_REGS_R11 * WORD_SIZE |
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#define VCPU_R12 __VCPU_REGS_R12 * WORD_SIZE |
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#define VCPU_R13 __VCPU_REGS_R13 * WORD_SIZE |
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#define VCPU_R14 __VCPU_REGS_R14 * WORD_SIZE |
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#define VCPU_R15 __VCPU_REGS_R15 * WORD_SIZE |
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#endif |
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.section .noinstr.text, "ax" |
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/** |
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* vmx_vmenter - VM-Enter the current loaded VMCS |
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* |
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* %RFLAGS.ZF: !VMCS.LAUNCHED, i.e. controls VMLAUNCH vs. VMRESUME |
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* |
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* Returns: |
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* %RFLAGS.CF is set on VM-Fail Invalid |
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* %RFLAGS.ZF is set on VM-Fail Valid |
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* %RFLAGS.{CF,ZF} are cleared on VM-Success, i.e. VM-Exit |
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* |
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* Note that VMRESUME/VMLAUNCH fall-through and return directly if |
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* they VM-Fail, whereas a successful VM-Enter + VM-Exit will jump |
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* to vmx_vmexit. |
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*/ |
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SYM_FUNC_START_LOCAL(vmx_vmenter) |
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/* EFLAGS.ZF is set if VMCS.LAUNCHED == 0 */ |
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je 2f |
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1: vmresume |
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ret |
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2: vmlaunch |
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ret |
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3: cmpb $0, kvm_rebooting |
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je 4f |
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ret |
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4: ud2 |
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_ASM_EXTABLE(1b, 3b) |
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_ASM_EXTABLE(2b, 3b) |
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SYM_FUNC_END(vmx_vmenter) |
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/** |
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* vmx_vmexit - Handle a VMX VM-Exit |
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* |
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* Returns: |
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* %RFLAGS.{CF,ZF} are cleared on VM-Success, i.e. VM-Exit |
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* |
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* This is vmx_vmenter's partner in crime. On a VM-Exit, control will jump |
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* here after hardware loads the host's state, i.e. this is the destination |
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* referred to by VMCS.HOST_RIP. |
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*/ |
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SYM_FUNC_START(vmx_vmexit) |
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#ifdef CONFIG_RETPOLINE |
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ALTERNATIVE "jmp .Lvmexit_skip_rsb", "", X86_FEATURE_RETPOLINE |
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/* Preserve guest's RAX, it's used to stuff the RSB. */ |
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push %_ASM_AX |
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/* IMPORTANT: Stuff the RSB immediately after VM-Exit, before RET! */ |
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FILL_RETURN_BUFFER %_ASM_AX, RSB_CLEAR_LOOPS, X86_FEATURE_RETPOLINE |
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/* Clear RFLAGS.CF and RFLAGS.ZF to preserve VM-Exit, i.e. !VM-Fail. */ |
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or $1, %_ASM_AX |
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pop %_ASM_AX |
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.Lvmexit_skip_rsb: |
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#endif |
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ret |
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SYM_FUNC_END(vmx_vmexit) |
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/** |
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* __vmx_vcpu_run - Run a vCPU via a transition to VMX guest mode |
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* @vmx: struct vcpu_vmx * (forwarded to vmx_update_host_rsp) |
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* @regs: unsigned long * (to guest registers) |
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* @launched: %true if the VMCS has been launched |
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* |
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* Returns: |
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* 0 on VM-Exit, 1 on VM-Fail |
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*/ |
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SYM_FUNC_START(__vmx_vcpu_run) |
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push %_ASM_BP |
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mov %_ASM_SP, %_ASM_BP |
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#ifdef CONFIG_X86_64 |
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push %r15 |
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push %r14 |
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push %r13 |
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push %r12 |
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#else |
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push %edi |
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push %esi |
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#endif |
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push %_ASM_BX |
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/* |
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* Save @regs, _ASM_ARG2 may be modified by vmx_update_host_rsp() and |
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* @regs is needed after VM-Exit to save the guest's register values. |
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*/ |
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push %_ASM_ARG2 |
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/* Copy @launched to BL, _ASM_ARG3 is volatile. */ |
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mov %_ASM_ARG3B, %bl |
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/* Adjust RSP to account for the CALL to vmx_vmenter(). */ |
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lea -WORD_SIZE(%_ASM_SP), %_ASM_ARG2 |
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call vmx_update_host_rsp |
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/* Load @regs to RAX. */ |
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mov (%_ASM_SP), %_ASM_AX |
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/* Check if vmlaunch or vmresume is needed */ |
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testb %bl, %bl |
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/* Load guest registers. Don't clobber flags. */ |
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mov VCPU_RCX(%_ASM_AX), %_ASM_CX |
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mov VCPU_RDX(%_ASM_AX), %_ASM_DX |
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mov VCPU_RBX(%_ASM_AX), %_ASM_BX |
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mov VCPU_RBP(%_ASM_AX), %_ASM_BP |
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mov VCPU_RSI(%_ASM_AX), %_ASM_SI |
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mov VCPU_RDI(%_ASM_AX), %_ASM_DI |
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#ifdef CONFIG_X86_64 |
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mov VCPU_R8 (%_ASM_AX), %r8 |
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mov VCPU_R9 (%_ASM_AX), %r9 |
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mov VCPU_R10(%_ASM_AX), %r10 |
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mov VCPU_R11(%_ASM_AX), %r11 |
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mov VCPU_R12(%_ASM_AX), %r12 |
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mov VCPU_R13(%_ASM_AX), %r13 |
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mov VCPU_R14(%_ASM_AX), %r14 |
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mov VCPU_R15(%_ASM_AX), %r15 |
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#endif |
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/* Load guest RAX. This kills the @regs pointer! */ |
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mov VCPU_RAX(%_ASM_AX), %_ASM_AX |
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/* Enter guest mode */ |
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call vmx_vmenter |
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/* Jump on VM-Fail. */ |
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jbe 2f |
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/* Temporarily save guest's RAX. */ |
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push %_ASM_AX |
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/* Reload @regs to RAX. */ |
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mov WORD_SIZE(%_ASM_SP), %_ASM_AX |
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/* Save all guest registers, including RAX from the stack */ |
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pop VCPU_RAX(%_ASM_AX) |
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mov %_ASM_CX, VCPU_RCX(%_ASM_AX) |
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mov %_ASM_DX, VCPU_RDX(%_ASM_AX) |
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mov %_ASM_BX, VCPU_RBX(%_ASM_AX) |
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mov %_ASM_BP, VCPU_RBP(%_ASM_AX) |
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mov %_ASM_SI, VCPU_RSI(%_ASM_AX) |
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mov %_ASM_DI, VCPU_RDI(%_ASM_AX) |
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#ifdef CONFIG_X86_64 |
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mov %r8, VCPU_R8 (%_ASM_AX) |
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mov %r9, VCPU_R9 (%_ASM_AX) |
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mov %r10, VCPU_R10(%_ASM_AX) |
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mov %r11, VCPU_R11(%_ASM_AX) |
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mov %r12, VCPU_R12(%_ASM_AX) |
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mov %r13, VCPU_R13(%_ASM_AX) |
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mov %r14, VCPU_R14(%_ASM_AX) |
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mov %r15, VCPU_R15(%_ASM_AX) |
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#endif |
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/* Clear RAX to indicate VM-Exit (as opposed to VM-Fail). */ |
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xor %eax, %eax |
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/* |
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* Clear all general purpose registers except RSP and RAX to prevent |
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* speculative use of the guest's values, even those that are reloaded |
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* via the stack. In theory, an L1 cache miss when restoring registers |
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* could lead to speculative execution with the guest's values. |
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* Zeroing XORs are dirt cheap, i.e. the extra paranoia is essentially |
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* free. RSP and RAX are exempt as RSP is restored by hardware during |
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* VM-Exit and RAX is explicitly loaded with 0 or 1 to return VM-Fail. |
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*/ |
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1: xor %ecx, %ecx |
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xor %edx, %edx |
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xor %ebx, %ebx |
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xor %ebp, %ebp |
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xor %esi, %esi |
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xor %edi, %edi |
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#ifdef CONFIG_X86_64 |
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xor %r8d, %r8d |
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xor %r9d, %r9d |
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xor %r10d, %r10d |
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xor %r11d, %r11d |
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xor %r12d, %r12d |
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xor %r13d, %r13d |
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xor %r14d, %r14d |
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xor %r15d, %r15d |
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#endif |
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/* "POP" @regs. */ |
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add $WORD_SIZE, %_ASM_SP |
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pop %_ASM_BX |
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#ifdef CONFIG_X86_64 |
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pop %r12 |
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pop %r13 |
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pop %r14 |
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pop %r15 |
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#else |
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pop %esi |
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pop %edi |
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#endif |
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pop %_ASM_BP |
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ret |
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/* VM-Fail. Out-of-line to avoid a taken Jcc after VM-Exit. */ |
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2: mov $1, %eax |
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jmp 1b |
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SYM_FUNC_END(__vmx_vcpu_run) |
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.section .text, "ax" |
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/** |
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* vmread_error_trampoline - Trampoline from inline asm to vmread_error() |
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* @field: VMCS field encoding that failed |
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* @fault: %true if the VMREAD faulted, %false if it failed |
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* Save and restore volatile registers across a call to vmread_error(). Note, |
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* all parameters are passed on the stack. |
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*/ |
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SYM_FUNC_START(vmread_error_trampoline) |
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push %_ASM_BP |
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mov %_ASM_SP, %_ASM_BP |
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push %_ASM_AX |
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push %_ASM_CX |
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push %_ASM_DX |
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#ifdef CONFIG_X86_64 |
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push %rdi |
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push %rsi |
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push %r8 |
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push %r9 |
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push %r10 |
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push %r11 |
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#endif |
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#ifdef CONFIG_X86_64 |
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/* Load @field and @fault to arg1 and arg2 respectively. */ |
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mov 3*WORD_SIZE(%rbp), %_ASM_ARG2 |
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mov 2*WORD_SIZE(%rbp), %_ASM_ARG1 |
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#else |
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/* Parameters are passed on the stack for 32-bit (see asmlinkage). */ |
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push 3*WORD_SIZE(%ebp) |
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push 2*WORD_SIZE(%ebp) |
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#endif |
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call vmread_error |
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#ifndef CONFIG_X86_64 |
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add $8, %esp |
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#endif |
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/* Zero out @fault, which will be popped into the result register. */ |
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_ASM_MOV $0, 3*WORD_SIZE(%_ASM_BP) |
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#ifdef CONFIG_X86_64 |
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pop %r11 |
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pop %r10 |
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pop %r9 |
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pop %r8 |
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pop %rsi |
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pop %rdi |
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#endif |
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pop %_ASM_DX |
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pop %_ASM_CX |
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pop %_ASM_AX |
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pop %_ASM_BP |
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ret |
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SYM_FUNC_END(vmread_error_trampoline) |
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SYM_FUNC_START(vmx_do_interrupt_nmi_irqoff) |
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/* |
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* Unconditionally create a stack frame, getting the correct RSP on the |
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* stack (for x86-64) would take two instructions anyways, and RBP can |
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* be used to restore RSP to make objtool happy (see below). |
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*/ |
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push %_ASM_BP |
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mov %_ASM_SP, %_ASM_BP |
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#ifdef CONFIG_X86_64 |
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/* |
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* Align RSP to a 16-byte boundary (to emulate CPU behavior) before |
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* creating the synthetic interrupt stack frame for the IRQ/NMI. |
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*/ |
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and $-16, %rsp |
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push $__KERNEL_DS |
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push %rbp |
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#endif |
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pushf |
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push $__KERNEL_CS |
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CALL_NOSPEC _ASM_ARG1 |
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/* |
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* "Restore" RSP from RBP, even though IRET has already unwound RSP to |
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* the correct value. objtool doesn't know the callee will IRET and, |
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* without the explicit restore, thinks the stack is getting walloped. |
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* Using an unwind hint is problematic due to x86-64's dynamic alignment. |
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*/ |
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mov %_ASM_BP, %_ASM_SP |
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pop %_ASM_BP |
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ret |
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SYM_FUNC_END(vmx_do_interrupt_nmi_irqoff)
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