arch/arm64/kvm/hyp-init.S

   1 /*
   2  * Copyright (C) 2012,2013 - ARM Ltd
   3  * Author: Marc Zyngier <marc.zyngier@arm.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License, version 2, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 #include <linux/linkage.h>
  19
  20 #include <asm/assembler.h>
  21 #include <asm/kvm_arm.h>
  22 #include <asm/kvm_mmu.h>
  23 #include <asm/pgtable-hwdef.h>
  24 #include <asm/sysreg.h>
  25 #include <asm/virt.h>
  26
  27         .text
  28         .pushsection    .hyp.idmap.text, "ax"
  29
  30         .align  11
  31
  32 ENTRY(__kvm_hyp_init)
  33         ventry  __invalid               // Synchronous EL2t
  34         ventry  __invalid               // IRQ EL2t
  35         ventry  __invalid               // FIQ EL2t
  36         ventry  __invalid               // Error EL2t
  37
  38         ventry  __invalid               // Synchronous EL2h
  39         ventry  __invalid               // IRQ EL2h
  40         ventry  __invalid               // FIQ EL2h
  41         ventry  __invalid               // Error EL2h
  42
  43         ventry  __do_hyp_init           // Synchronous 64-bit EL1
  44         ventry  __invalid               // IRQ 64-bit EL1
  45         ventry  __invalid               // FIQ 64-bit EL1
  46         ventry  __invalid               // Error 64-bit EL1
  47
  48         ventry  __invalid               // Synchronous 32-bit EL1
  49         ventry  __invalid               // IRQ 32-bit EL1
  50         ventry  __invalid               // FIQ 32-bit EL1
  51         ventry  __invalid               // Error 32-bit EL1
  52
  53 __invalid:
  54         b       .
  55
  56         /*
  57          * x0: HYP pgd
  58          * x1: HYP stack
  59          * x2: HYP vectors
  60          */
  61 __do_hyp_init:
  62         /* Check for a stub HVC call */
  63         cmp     x0, #HVC_STUB_HCALL_NR
  64         b.lo    __kvm_handle_stub_hvc
  65
  66         msr     ttbr0_el2, x0
  67
  68         mrs     x4, tcr_el1
  69         ldr     x5, =TCR_EL2_MASK
  70         and     x4, x4, x5
  71         mov     x5, #TCR_EL2_RES1
  72         orr     x4, x4, x5
  73
  74 #ifndef CONFIG_ARM64_VA_BITS_48
  75         /*
  76          * If we are running with VA_BITS < 48, we may be running with an extra
  77          * level of translation in the ID map. This is only the case if system
  78          * RAM is out of range for the currently configured page size and number
  79          * of translation levels, in which case we will also need the extra
  80          * level for the HYP ID map, or we won't be able to enable the EL2 MMU.
  81          *
  82          * However, at EL2, there is only one TTBR register, and we can't switch
  83          * between translation tables *and* update TCR_EL2.T0SZ at the same
  84          * time. Bottom line: we need the extra level in *both* our translation
  85          * tables.
  86          *
  87          * So use the same T0SZ value we use for the ID map.
  88          */
  89         ldr_l   x5, idmap_t0sz
  90         bfi     x4, x5, TCR_T0SZ_OFFSET, TCR_TxSZ_WIDTH
  91 #endif
  92         /*
  93          * Read the PARange bits from ID_AA64MMFR0_EL1 and set the PS bits in
  94          * TCR_EL2.
  95          */
  96         mrs     x5, ID_AA64MMFR0_EL1
  97         bfi     x4, x5, #16, #3
  98
  99         msr     tcr_el2, x4
 100
 101         mrs     x4, mair_el1
 102         msr     mair_el2, x4
 103         isb
 104
 105         /* Invalidate the stale TLBs from Bootloader */
 106         tlbi    alle2
 107         dsb     sy
 108
 109         /*
 110          * Preserve all the RES1 bits while setting the default flags,
 111          * as well as the EE bit on BE. Drop the A flag since the compiler
 112          * is allowed to generate unaligned accesses.
 113          */
 114         ldr     x4, =(SCTLR_EL2_RES1 | (SCTLR_ELx_FLAGS & ~SCTLR_ELx_A))
 115 CPU_BE( orr     x4, x4, #SCTLR_ELx_EE)
 116         msr     sctlr_el2, x4
 117         isb
 118
 119         /* Set the stack and new vectors */
 120         kern_hyp_va     x1
 121         mov     sp, x1
 122         kern_hyp_va     x2
 123         msr     vbar_el2, x2
 124
 125         /* Hello, World! */
 126         eret
 127 ENDPROC(__kvm_hyp_init)
 128
 129 ENTRY(__kvm_handle_stub_hvc)
 130         cmp     x0, #HVC_SOFT_RESTART
 131         b.ne    1f
 132
 133         /* This is where we're about to jump, staying at EL2 */
 134         msr     elr_el2, x1
 135         mov     x0, #(PSR_F_BIT | PSR_I_BIT | PSR_A_BIT | PSR_D_BIT | PSR_MODE_EL2h)
 136         msr     spsr_el2, x0
 137
 138         /* Shuffle the arguments, and don't come back */
 139         mov     x0, x2
 140         mov     x1, x3
 141         mov     x2, x4
 142         b       reset
 143
 144 1:      cmp     x0, #HVC_RESET_VECTORS
 145         b.ne    1f
 146 reset:
 147         /*
 148          * Reset kvm back to the hyp stub. Do not clobber x0-x4 in
 149          * case we coming via HVC_SOFT_RESTART.
 150          */
 151         mrs     x5, sctlr_el2
 152         ldr     x6, =SCTLR_ELx_FLAGS
 153         bic     x5, x5, x6              // Clear SCTL_M and etc
 154         msr     sctlr_el2, x5
 155         isb
 156
 157         /* Install stub vectors */
 158         adr_l   x5, __hyp_stub_vectors
 159         msr     vbar_el2, x5
 160         mov     x0, xzr
 161         eret
 162
 163 1:      /* Bad stub call */
 164         ldr     x0, =HVC_STUB_ERR
 165         eret
 166
 167 ENDPROC(__kvm_handle_stub_hvc)
 168
 169         .ltorg
 170
 171         .popsection