arch/arm/kvm/hyp/switch.c

   1 /*
   2  * Copyright (C) 2015 - 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 #include <linux/jump_label.h>
  18
  19 #include <asm/kvm_asm.h>
  20 #include <asm/kvm_hyp.h>
  21
  22 __asm__(".arch_extension     virt");
  23
  24 /*
  25  * Activate the traps, saving the host's fpexc register before
  26  * overwriting it. We'll restore it on VM exit.
  27  */
  28 static void __hyp_text __activate_traps(struct kvm_vcpu *vcpu, u32 *fpexc_host)
  29 {
  30         u32 val;
  31
  32         /*
  33          * We are about to set HCPTR.TCP10/11 to trap all floating point
  34          * register accesses to HYP, however, the ARM ARM clearly states that
  35          * traps are only taken to HYP if the operation would not otherwise
  36          * trap to SVC.  Therefore, always make sure that for 32-bit guests,
  37          * we set FPEXC.EN to prevent traps to SVC, when setting the TCP bits.
  38          */
  39         val = read_sysreg(VFP_FPEXC);
  40         *fpexc_host = val;
  41         if (!(val & FPEXC_EN)) {
  42                 write_sysreg(val | FPEXC_EN, VFP_FPEXC);
  43                 isb();
  44         }
  45
  46         write_sysreg(vcpu->arch.hcr | vcpu->arch.irq_lines, HCR);
  47         /* Trap on AArch32 cp15 c15 accesses (EL1 or EL0) */
  48         write_sysreg(HSTR_T(15), HSTR);
  49         write_sysreg(HCPTR_TTA | HCPTR_TCP(10) | HCPTR_TCP(11), HCPTR);
  50         val = read_sysreg(HDCR);
  51         val |= HDCR_TPM | HDCR_TPMCR; /* trap performance monitors */
  52         val |= HDCR_TDRA | HDCR_TDOSA | HDCR_TDA; /* trap debug regs */
  53         write_sysreg(val, HDCR);
  54 }
  55
  56 static void __hyp_text __deactivate_traps(struct kvm_vcpu *vcpu)
  57 {
  58         u32 val;
  59
  60         /*
  61          * If we pended a virtual abort, preserve it until it gets
  62          * cleared. See B1.9.9 (Virtual Abort exception) for details,
  63          * but the crucial bit is the zeroing of HCR.VA in the
  64          * pseudocode.
  65          */
  66         if (vcpu->arch.hcr & HCR_VA)
  67                 vcpu->arch.hcr = read_sysreg(HCR);
  68
  69         write_sysreg(0, HCR);
  70         write_sysreg(0, HSTR);
  71         val = read_sysreg(HDCR);
  72         write_sysreg(val & ~(HDCR_TPM | HDCR_TPMCR), HDCR);
  73         write_sysreg(0, HCPTR);
  74 }
  75
  76 static void __hyp_text __activate_vm(struct kvm_vcpu *vcpu)
  77 {
  78         struct kvm *kvm = kern_hyp_va(vcpu->kvm);
  79         write_sysreg(kvm->arch.vttbr, VTTBR);
  80         write_sysreg(vcpu->arch.midr, VPIDR);
  81 }
  82
  83 static void __hyp_text __deactivate_vm(struct kvm_vcpu *vcpu)
  84 {
  85         write_sysreg(0, VTTBR);
  86         write_sysreg(read_sysreg(MIDR), VPIDR);
  87 }
  88
  89
  90 static void __hyp_text __vgic_save_state(struct kvm_vcpu *vcpu)
  91 {
  92         if (static_branch_unlikely(&kvm_vgic_global_state.gicv3_cpuif))
  93                 __vgic_v3_save_state(vcpu);
  94         else
  95                 __vgic_v2_save_state(vcpu);
  96 }
  97
  98 static void __hyp_text __vgic_restore_state(struct kvm_vcpu *vcpu)
  99 {
 100         if (static_branch_unlikely(&kvm_vgic_global_state.gicv3_cpuif))
 101                 __vgic_v3_restore_state(vcpu);
 102         else
 103                 __vgic_v2_restore_state(vcpu);
 104 }
 105
 106 static bool __hyp_text __populate_fault_info(struct kvm_vcpu *vcpu)
 107 {
 108         u32 hsr = read_sysreg(HSR);
 109         u8 ec = hsr >> HSR_EC_SHIFT;
 110         u32 hpfar, far;
 111
 112         vcpu->arch.fault.hsr = hsr;
 113
 114         if (ec == HSR_EC_IABT)
 115                 far = read_sysreg(HIFAR);
 116         else if (ec == HSR_EC_DABT)
 117                 far = read_sysreg(HDFAR);
 118         else
 119                 return true;
 120
 121         /*
 122          * B3.13.5 Reporting exceptions taken to the Non-secure PL2 mode:
 123          *
 124          * Abort on the stage 2 translation for a memory access from a
 125          * Non-secure PL1 or PL0 mode:
 126          *
 127          * For any Access flag fault or Translation fault, and also for any
 128          * Permission fault on the stage 2 translation of a memory access
 129          * made as part of a translation table walk for a stage 1 translation,
 130          * the HPFAR holds the IPA that caused the fault. Otherwise, the HPFAR
 131          * is UNKNOWN.
 132          */
 133         if (!(hsr & HSR_DABT_S1PTW) && (hsr & HSR_FSC_TYPE) == FSC_PERM) {
 134                 u64 par, tmp;
 135
 136                 par = read_sysreg(PAR);
 137                 write_sysreg(far, ATS1CPR);
 138                 isb();
 139
 140                 tmp = read_sysreg(PAR);
 141                 write_sysreg(par, PAR);
 142
 143                 if (unlikely(tmp & 1))
 144                         return false; /* Translation failed, back to guest */
 145
 146                 hpfar = ((tmp >> 12) & ((1UL << 28) - 1)) << 4;
 147         } else {
 148                 hpfar = read_sysreg(HPFAR);
 149         }
 150
 151         vcpu->arch.fault.hxfar = far;
 152         vcpu->arch.fault.hpfar = hpfar;
 153         return true;
 154 }
 155
 156 int __hyp_text __kvm_vcpu_run(struct kvm_vcpu *vcpu)
 157 {
 158         struct kvm_cpu_context *host_ctxt;
 159         struct kvm_cpu_context *guest_ctxt;
 160         bool fp_enabled;
 161         u64 exit_code;
 162         u32 fpexc;
 163
 164         vcpu = kern_hyp_va(vcpu);
 165         write_sysreg(vcpu, HTPIDR);
 166
 167         host_ctxt = kern_hyp_va(vcpu->arch.host_cpu_context);
 168         guest_ctxt = &vcpu->arch.ctxt;
 169
 170         __sysreg_save_state(host_ctxt);
 171         __banked_save_state(host_ctxt);
 172
 173         __activate_traps(vcpu, &fpexc);
 174         __activate_vm(vcpu);
 175
 176         __vgic_restore_state(vcpu);
 177         __timer_restore_state(vcpu);
 178
 179         __sysreg_restore_state(guest_ctxt);
 180         __banked_restore_state(guest_ctxt);
 181
 182         /* Jump in the fire! */
 183 again:
 184         exit_code = __guest_enter(vcpu, host_ctxt);
 185         /* And we're baaack! */
 186
 187         if (exit_code == ARM_EXCEPTION_HVC && !__populate_fault_info(vcpu))
 188                 goto again;
 189
 190         fp_enabled = __vfp_enabled();
 191
 192         __banked_save_state(guest_ctxt);
 193         __sysreg_save_state(guest_ctxt);
 194         __timer_save_state(vcpu);
 195         __vgic_save_state(vcpu);
 196
 197         __deactivate_traps(vcpu);
 198         __deactivate_vm(vcpu);
 199
 200         __banked_restore_state(host_ctxt);
 201         __sysreg_restore_state(host_ctxt);
 202
 203         if (fp_enabled) {
 204                 __vfp_save_state(&guest_ctxt->vfp);
 205                 __vfp_restore_state(&host_ctxt->vfp);
 206         }
 207
 208         write_sysreg(fpexc, VFP_FPEXC);
 209
 210         return exit_code;
 211 }
 212
 213 static const char * const __hyp_panic_string[] = {
 214         [ARM_EXCEPTION_RESET]      = "\nHYP panic: RST   PC:%08x CPSR:%08x",
 215         [ARM_EXCEPTION_UNDEFINED]  = "\nHYP panic: UNDEF PC:%08x CPSR:%08x",
 216         [ARM_EXCEPTION_SOFTWARE]   = "\nHYP panic: SVC   PC:%08x CPSR:%08x",
 217         [ARM_EXCEPTION_PREF_ABORT] = "\nHYP panic: PABRT PC:%08x CPSR:%08x",
 218         [ARM_EXCEPTION_DATA_ABORT] = "\nHYP panic: DABRT PC:%08x ADDR:%08x",
 219         [ARM_EXCEPTION_IRQ]        = "\nHYP panic: IRQ   PC:%08x CPSR:%08x",
 220         [ARM_EXCEPTION_FIQ]        = "\nHYP panic: FIQ   PC:%08x CPSR:%08x",
 221         [ARM_EXCEPTION_HVC]        = "\nHYP panic: HVC   PC:%08x CPSR:%08x",
 222 };
 223
 224 void __hyp_text __noreturn __hyp_panic(int cause)
 225 {
 226         u32 elr = read_special(ELR_hyp);
 227         u32 val;
 228
 229         if (cause == ARM_EXCEPTION_DATA_ABORT)
 230                 val = read_sysreg(HDFAR);
 231         else
 232                 val = read_special(SPSR);
 233
 234         if (read_sysreg(VTTBR)) {
 235                 struct kvm_vcpu *vcpu;
 236                 struct kvm_cpu_context *host_ctxt;
 237
 238                 vcpu = (struct kvm_vcpu *)read_sysreg(HTPIDR);
 239                 host_ctxt = kern_hyp_va(vcpu->arch.host_cpu_context);
 240                 __deactivate_traps(vcpu);
 241                 __deactivate_vm(vcpu);
 242                 __sysreg_restore_state(host_ctxt);
 243         }
 244
 245         /* Call panic for real */
 246         __hyp_do_panic(__hyp_panic_string[cause], elr, val);
 247
 248         unreachable();
 249 }