1 /* SPDX-License-Identifier: GPL-2.0 */
2 #include <linux/linkage.h>
4 #include <asm/bitsperlong.h>
5 #include <asm/kvm_vcpu_regs.h>
6 #include <asm/nospec-branch.h>
7 #include <asm/segment.h>
9 #define WORD_SIZE (BITS_PER_LONG / 8)
11 #define VCPU_RAX __VCPU_REGS_RAX * WORD_SIZE
12 #define VCPU_RCX __VCPU_REGS_RCX * WORD_SIZE
13 #define VCPU_RDX __VCPU_REGS_RDX * WORD_SIZE
14 #define VCPU_RBX __VCPU_REGS_RBX * WORD_SIZE
15 /* Intentionally omit RSP as it's context switched by hardware */
16 #define VCPU_RBP __VCPU_REGS_RBP * WORD_SIZE
17 #define VCPU_RSI __VCPU_REGS_RSI * WORD_SIZE
18 #define VCPU_RDI __VCPU_REGS_RDI * WORD_SIZE
21 #define VCPU_R8 __VCPU_REGS_R8 * WORD_SIZE
22 #define VCPU_R9 __VCPU_REGS_R9 * WORD_SIZE
23 #define VCPU_R10 __VCPU_REGS_R10 * WORD_SIZE
24 #define VCPU_R11 __VCPU_REGS_R11 * WORD_SIZE
25 #define VCPU_R12 __VCPU_REGS_R12 * WORD_SIZE
26 #define VCPU_R13 __VCPU_REGS_R13 * WORD_SIZE
27 #define VCPU_R14 __VCPU_REGS_R14 * WORD_SIZE
28 #define VCPU_R15 __VCPU_REGS_R15 * WORD_SIZE
31 .section .noinstr.text, "ax"
34 * vmx_vmenter - VM-Enter the current loaded VMCS
36 * %RFLAGS.ZF: !VMCS.LAUNCHED, i.e. controls VMLAUNCH vs. VMRESUME
39 * %RFLAGS.CF is set on VM-Fail Invalid
40 * %RFLAGS.ZF is set on VM-Fail Valid
41 * %RFLAGS.{CF,ZF} are cleared on VM-Success, i.e. VM-Exit
43 * Note that VMRESUME/VMLAUNCH fall-through and return directly if
44 * they VM-Fail, whereas a successful VM-Enter + VM-Exit will jump
47 SYM_FUNC_START_LOCAL(vmx_vmenter)
48 /* EFLAGS.ZF is set if VMCS.LAUNCHED == 0 */
57 3: cmpb $0, kvm_rebooting
65 SYM_FUNC_END(vmx_vmenter)
68 * vmx_vmexit - Handle a VMX VM-Exit
71 * %RFLAGS.{CF,ZF} are cleared on VM-Success, i.e. VM-Exit
73 * This is vmx_vmenter's partner in crime. On a VM-Exit, control will jump
74 * here after hardware loads the host's state, i.e. this is the destination
75 * referred to by VMCS.HOST_RIP.
77 SYM_FUNC_START(vmx_vmexit)
78 #ifdef CONFIG_RETPOLINE
79 ALTERNATIVE "jmp .Lvmexit_skip_rsb", "", X86_FEATURE_RETPOLINE
80 /* Preserve guest's RAX, it's used to stuff the RSB. */
83 /* IMPORTANT: Stuff the RSB immediately after VM-Exit, before RET! */
84 FILL_RETURN_BUFFER %_ASM_AX, RSB_CLEAR_LOOPS, X86_FEATURE_RETPOLINE
86 /* Clear RFLAGS.CF and RFLAGS.ZF to preserve VM-Exit, i.e. !VM-Fail. */
93 SYM_FUNC_END(vmx_vmexit)
96 * __vmx_vcpu_run - Run a vCPU via a transition to VMX guest mode
97 * @vmx: struct vcpu_vmx * (forwarded to vmx_update_host_rsp)
98 * @regs: unsigned long * (to guest registers)
99 * @launched: %true if the VMCS has been launched
102 * 0 on VM-Exit, 1 on VM-Fail
104 SYM_FUNC_START(__vmx_vcpu_run)
106 mov %_ASM_SP, %_ASM_BP
119 * Save @regs, _ASM_ARG2 may be modified by vmx_update_host_rsp() and
120 * @regs is needed after VM-Exit to save the guest's register values.
124 /* Copy @launched to BL, _ASM_ARG3 is volatile. */
127 /* Adjust RSP to account for the CALL to vmx_vmenter(). */
128 lea -WORD_SIZE(%_ASM_SP), %_ASM_ARG2
129 call vmx_update_host_rsp
131 /* Load @regs to RAX. */
132 mov (%_ASM_SP), %_ASM_AX
134 /* Check if vmlaunch or vmresume is needed */
137 /* Load guest registers. Don't clobber flags. */
138 mov VCPU_RCX(%_ASM_AX), %_ASM_CX
139 mov VCPU_RDX(%_ASM_AX), %_ASM_DX
140 mov VCPU_RBX(%_ASM_AX), %_ASM_BX
141 mov VCPU_RBP(%_ASM_AX), %_ASM_BP
142 mov VCPU_RSI(%_ASM_AX), %_ASM_SI
143 mov VCPU_RDI(%_ASM_AX), %_ASM_DI
145 mov VCPU_R8 (%_ASM_AX), %r8
146 mov VCPU_R9 (%_ASM_AX), %r9
147 mov VCPU_R10(%_ASM_AX), %r10
148 mov VCPU_R11(%_ASM_AX), %r11
149 mov VCPU_R12(%_ASM_AX), %r12
150 mov VCPU_R13(%_ASM_AX), %r13
151 mov VCPU_R14(%_ASM_AX), %r14
152 mov VCPU_R15(%_ASM_AX), %r15
154 /* Load guest RAX. This kills the @regs pointer! */
155 mov VCPU_RAX(%_ASM_AX), %_ASM_AX
157 /* Enter guest mode */
160 /* Jump on VM-Fail. */
163 /* Temporarily save guest's RAX. */
166 /* Reload @regs to RAX. */
167 mov WORD_SIZE(%_ASM_SP), %_ASM_AX
169 /* Save all guest registers, including RAX from the stack */
170 pop VCPU_RAX(%_ASM_AX)
171 mov %_ASM_CX, VCPU_RCX(%_ASM_AX)
172 mov %_ASM_DX, VCPU_RDX(%_ASM_AX)
173 mov %_ASM_BX, VCPU_RBX(%_ASM_AX)
174 mov %_ASM_BP, VCPU_RBP(%_ASM_AX)
175 mov %_ASM_SI, VCPU_RSI(%_ASM_AX)
176 mov %_ASM_DI, VCPU_RDI(%_ASM_AX)
178 mov %r8, VCPU_R8 (%_ASM_AX)
179 mov %r9, VCPU_R9 (%_ASM_AX)
180 mov %r10, VCPU_R10(%_ASM_AX)
181 mov %r11, VCPU_R11(%_ASM_AX)
182 mov %r12, VCPU_R12(%_ASM_AX)
183 mov %r13, VCPU_R13(%_ASM_AX)
184 mov %r14, VCPU_R14(%_ASM_AX)
185 mov %r15, VCPU_R15(%_ASM_AX)
188 /* Clear RAX to indicate VM-Exit (as opposed to VM-Fail). */
192 * Clear all general purpose registers except RSP and RAX to prevent
193 * speculative use of the guest's values, even those that are reloaded
194 * via the stack. In theory, an L1 cache miss when restoring registers
195 * could lead to speculative execution with the guest's values.
196 * Zeroing XORs are dirt cheap, i.e. the extra paranoia is essentially
197 * free. RSP and RAX are exempt as RSP is restored by hardware during
198 * VM-Exit and RAX is explicitly loaded with 0 or 1 to return VM-Fail.
218 add $WORD_SIZE, %_ASM_SP
233 /* VM-Fail. Out-of-line to avoid a taken Jcc after VM-Exit. */
236 SYM_FUNC_END(__vmx_vcpu_run)
242 * vmread_error_trampoline - Trampoline from inline asm to vmread_error()
243 * @field: VMCS field encoding that failed
244 * @fault: %true if the VMREAD faulted, %false if it failed
246 * Save and restore volatile registers across a call to vmread_error(). Note,
247 * all parameters are passed on the stack.
249 SYM_FUNC_START(vmread_error_trampoline)
251 mov %_ASM_SP, %_ASM_BP
265 /* Load @field and @fault to arg1 and arg2 respectively. */
266 mov 3*WORD_SIZE(%rbp), %_ASM_ARG2
267 mov 2*WORD_SIZE(%rbp), %_ASM_ARG1
269 /* Parameters are passed on the stack for 32-bit (see asmlinkage). */
270 push 3*WORD_SIZE(%ebp)
271 push 2*WORD_SIZE(%ebp)
276 #ifndef CONFIG_X86_64
280 /* Zero out @fault, which will be popped into the result register. */
281 _ASM_MOV $0, 3*WORD_SIZE(%_ASM_BP)
297 SYM_FUNC_END(vmread_error_trampoline)
299 SYM_FUNC_START(vmx_do_interrupt_nmi_irqoff)
301 * Unconditionally create a stack frame, getting the correct RSP on the
302 * stack (for x86-64) would take two instructions anyways, and RBP can
303 * be used to restore RSP to make objtool happy (see below).
306 mov %_ASM_SP, %_ASM_BP
310 * Align RSP to a 16-byte boundary (to emulate CPU behavior) before
311 * creating the synthetic interrupt stack frame for the IRQ/NMI.
319 CALL_NOSPEC _ASM_ARG1
322 * "Restore" RSP from RBP, even though IRET has already unwound RSP to
323 * the correct value. objtool doesn't know the callee will IRET and,
324 * without the explicit restore, thinks the stack is getting walloped.
325 * Using an unwind hint is problematic due to x86-64's dynamic alignment.
327 mov %_ASM_BP, %_ASM_SP
330 SYM_FUNC_END(vmx_do_interrupt_nmi_irqoff)