arch/x86/kvm/svm/vmenter.S

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #include <linux/linkage.h>
   3 #include <asm/asm.h>
   4 #include <asm/bitsperlong.h>
   5 #include <asm/kvm_vcpu_regs.h>
   6 #include <asm/nospec-branch.h>
   7
   8 #define WORD_SIZE (BITS_PER_LONG / 8)
   9
  10 /* Intentionally omit RAX as it's context switched by hardware */
  11 #define VCPU_RCX        __VCPU_REGS_RCX * WORD_SIZE
  12 #define VCPU_RDX        __VCPU_REGS_RDX * WORD_SIZE
  13 #define VCPU_RBX        __VCPU_REGS_RBX * WORD_SIZE
  14 /* Intentionally omit RSP as it's context switched by hardware */
  15 #define VCPU_RBP        __VCPU_REGS_RBP * WORD_SIZE
  16 #define VCPU_RSI        __VCPU_REGS_RSI * WORD_SIZE
  17 #define VCPU_RDI        __VCPU_REGS_RDI * WORD_SIZE
  18
  19 #ifdef CONFIG_X86_64
  20 #define VCPU_R8         __VCPU_REGS_R8  * WORD_SIZE
  21 #define VCPU_R9         __VCPU_REGS_R9  * WORD_SIZE
  22 #define VCPU_R10        __VCPU_REGS_R10 * WORD_SIZE
  23 #define VCPU_R11        __VCPU_REGS_R11 * WORD_SIZE
  24 #define VCPU_R12        __VCPU_REGS_R12 * WORD_SIZE
  25 #define VCPU_R13        __VCPU_REGS_R13 * WORD_SIZE
  26 #define VCPU_R14        __VCPU_REGS_R14 * WORD_SIZE
  27 #define VCPU_R15        __VCPU_REGS_R15 * WORD_SIZE
  28 #endif
  29
  30 .section .noinstr.text, "ax"
  31
  32 /**
  33  * __svm_vcpu_run - Run a vCPU via a transition to SVM guest mode
  34  * @vmcb_pa:    unsigned long
  35  * @regs:       unsigned long * (to guest registers)
  36  */
  37 SYM_FUNC_START(__svm_vcpu_run)
  38         push %_ASM_BP
  39 #ifdef CONFIG_X86_64
  40         push %r15
  41         push %r14
  42         push %r13
  43         push %r12
  44 #else
  45         push %edi
  46         push %esi
  47 #endif
  48         push %_ASM_BX
  49
  50         /* Save @regs. */
  51         push %_ASM_ARG2
  52
  53         /* Save @vmcb. */
  54         push %_ASM_ARG1
  55
  56         /* Move @regs to RAX. */
  57         mov %_ASM_ARG2, %_ASM_AX
  58
  59         /* Load guest registers. */
  60         mov VCPU_RCX(%_ASM_AX), %_ASM_CX
  61         mov VCPU_RDX(%_ASM_AX), %_ASM_DX
  62         mov VCPU_RBX(%_ASM_AX), %_ASM_BX
  63         mov VCPU_RBP(%_ASM_AX), %_ASM_BP
  64         mov VCPU_RSI(%_ASM_AX), %_ASM_SI
  65         mov VCPU_RDI(%_ASM_AX), %_ASM_DI
  66 #ifdef CONFIG_X86_64
  67         mov VCPU_R8 (%_ASM_AX),  %r8
  68         mov VCPU_R9 (%_ASM_AX),  %r9
  69         mov VCPU_R10(%_ASM_AX), %r10
  70         mov VCPU_R11(%_ASM_AX), %r11
  71         mov VCPU_R12(%_ASM_AX), %r12
  72         mov VCPU_R13(%_ASM_AX), %r13
  73         mov VCPU_R14(%_ASM_AX), %r14
  74         mov VCPU_R15(%_ASM_AX), %r15
  75 #endif
  76
  77         /* "POP" @vmcb to RAX. */
  78         pop %_ASM_AX
  79
  80         /* Enter guest mode */
  81         sti
  82 1:      vmload %_ASM_AX
  83         jmp 3f
  84 2:      cmpb $0, kvm_rebooting
  85         jne 3f
  86         ud2
  87         _ASM_EXTABLE(1b, 2b)
  88
  89 3:      vmrun %_ASM_AX
  90         jmp 5f
  91 4:      cmpb $0, kvm_rebooting
  92         jne 5f
  93         ud2
  94         _ASM_EXTABLE(3b, 4b)
  95
  96 5:      vmsave %_ASM_AX
  97         jmp 7f
  98 6:      cmpb $0, kvm_rebooting
  99         jne 7f
 100         ud2
 101         _ASM_EXTABLE(5b, 6b)
 102 7:
 103         cli
 104
 105 #ifdef CONFIG_RETPOLINE
 106         /* IMPORTANT: Stuff the RSB immediately after VM-Exit, before RET! */
 107         FILL_RETURN_BUFFER %_ASM_AX, RSB_CLEAR_LOOPS, X86_FEATURE_RETPOLINE
 108 #endif
 109
 110         /* "POP" @regs to RAX. */
 111         pop %_ASM_AX
 112
 113         /* Save all guest registers.  */
 114         mov %_ASM_CX,   VCPU_RCX(%_ASM_AX)
 115         mov %_ASM_DX,   VCPU_RDX(%_ASM_AX)
 116         mov %_ASM_BX,   VCPU_RBX(%_ASM_AX)
 117         mov %_ASM_BP,   VCPU_RBP(%_ASM_AX)
 118         mov %_ASM_SI,   VCPU_RSI(%_ASM_AX)
 119         mov %_ASM_DI,   VCPU_RDI(%_ASM_AX)
 120 #ifdef CONFIG_X86_64
 121         mov %r8,  VCPU_R8 (%_ASM_AX)
 122         mov %r9,  VCPU_R9 (%_ASM_AX)
 123         mov %r10, VCPU_R10(%_ASM_AX)
 124         mov %r11, VCPU_R11(%_ASM_AX)
 125         mov %r12, VCPU_R12(%_ASM_AX)
 126         mov %r13, VCPU_R13(%_ASM_AX)
 127         mov %r14, VCPU_R14(%_ASM_AX)
 128         mov %r15, VCPU_R15(%_ASM_AX)
 129 #endif
 130
 131         /*
 132          * Clear all general purpose registers except RSP and RAX to prevent
 133          * speculative use of the guest's values, even those that are reloaded
 134          * via the stack.  In theory, an L1 cache miss when restoring registers
 135          * could lead to speculative execution with the guest's values.
 136          * Zeroing XORs are dirt cheap, i.e. the extra paranoia is essentially
 137          * free.  RSP and RAX are exempt as they are restored by hardware
 138          * during VM-Exit.
 139          */
 140         xor %ecx, %ecx
 141         xor %edx, %edx
 142         xor %ebx, %ebx
 143         xor %ebp, %ebp
 144         xor %esi, %esi
 145         xor %edi, %edi
 146 #ifdef CONFIG_X86_64
 147         xor %r8d,  %r8d
 148         xor %r9d,  %r9d
 149         xor %r10d, %r10d
 150         xor %r11d, %r11d
 151         xor %r12d, %r12d
 152         xor %r13d, %r13d
 153         xor %r14d, %r14d
 154         xor %r15d, %r15d
 155 #endif
 156
 157         pop %_ASM_BX
 158
 159 #ifdef CONFIG_X86_64
 160         pop %r12
 161         pop %r13
 162         pop %r14
 163         pop %r15
 164 #else
 165         pop %esi
 166         pop %edi
 167 #endif
 168         pop %_ASM_BP
 169         ret
 170 SYM_FUNC_END(__svm_vcpu_run)