arch/powerpc/kvm/book3s_hv_tm_builtin.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright 2017 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
   4  */
   5
   6 #include <linux/kvm_host.h>
   7
   8 #include <asm/kvm_ppc.h>
   9 #include <asm/kvm_book3s.h>
  10 #include <asm/kvm_book3s_64.h>
  11 #include <asm/reg.h>
  12 #include <asm/ppc-opcode.h>
  13
  14 /*
  15  * This handles the cases where the guest is in real suspend mode
  16  * and we want to get back to the guest without dooming the transaction.
  17  * The caller has checked that the guest is in real-suspend mode
  18  * (MSR[TS] = S and the fake-suspend flag is not set).
  19  */
  20 int kvmhv_p9_tm_emulation_early(struct kvm_vcpu *vcpu)
  21 {
  22         u32 instr = vcpu->arch.emul_inst;
  23         u64 newmsr, msr, bescr;
  24         int rs;
  25
  26         /*
  27          * rfid, rfebb, and mtmsrd encode bit 31 = 0 since it's a reserved bit
  28          * in these instructions, so masking bit 31 out doesn't change these
  29          * instructions. For the tsr. instruction if bit 31 = 0 then it is per
  30          * ISA an invalid form, however P9 UM, in section 4.6.10 Book II Invalid
  31          * Forms, informs specifically that ignoring bit 31 is an acceptable way
  32          * to handle TM-related invalid forms that have bit 31 = 0. Moreover,
  33          * for emulation purposes both forms (w/ and wo/ bit 31 set) can
  34          * generate a softpatch interrupt. Hence both forms are handled below
  35          * for tsr. to make them behave the same way.
  36          */
  37         switch (instr & PO_XOP_OPCODE_MASK) {
  38         case PPC_INST_RFID:
  39                 /* XXX do we need to check for PR=0 here? */
  40                 newmsr = vcpu->arch.shregs.srr1;
  41                 /* should only get here for Sx -> T1 transition */
  42                 if (!(MSR_TM_TRANSACTIONAL(newmsr) && (newmsr & MSR_TM)))
  43                         return 0;
  44                 newmsr = sanitize_msr(newmsr);
  45                 vcpu->arch.shregs.msr = newmsr;
  46                 vcpu->arch.cfar = vcpu->arch.regs.nip - 4;
  47                 vcpu->arch.regs.nip = vcpu->arch.shregs.srr0;
  48                 return 1;
  49
  50         case PPC_INST_RFEBB:
  51                 /* check for PR=1 and arch 2.06 bit set in PCR */
  52                 msr = vcpu->arch.shregs.msr;
  53                 if ((msr & MSR_PR) && (vcpu->arch.vcore->pcr & PCR_ARCH_206))
  54                         return 0;
  55                 /* check EBB facility is available */
  56                 if (!(vcpu->arch.hfscr & HFSCR_EBB) ||
  57                     ((msr & MSR_PR) && !(mfspr(SPRN_FSCR) & FSCR_EBB)))
  58                         return 0;
  59                 bescr = mfspr(SPRN_BESCR);
  60                 /* expect to see a S->T transition requested */
  61                 if (((bescr >> 30) & 3) != 2)
  62                         return 0;
  63                 bescr &= ~BESCR_GE;
  64                 if (instr & (1 << 11))
  65                         bescr |= BESCR_GE;
  66                 mtspr(SPRN_BESCR, bescr);
  67                 msr = (msr & ~MSR_TS_MASK) | MSR_TS_T;
  68                 vcpu->arch.shregs.msr = msr;
  69                 vcpu->arch.cfar = vcpu->arch.regs.nip - 4;
  70                 vcpu->arch.regs.nip = mfspr(SPRN_EBBRR);
  71                 return 1;
  72
  73         case PPC_INST_MTMSRD:
  74                 /* XXX do we need to check for PR=0 here? */
  75                 rs = (instr >> 21) & 0x1f;
  76                 newmsr = kvmppc_get_gpr(vcpu, rs);
  77                 msr = vcpu->arch.shregs.msr;
  78                 /* check this is a Sx -> T1 transition */
  79                 if (!(MSR_TM_TRANSACTIONAL(newmsr) && (newmsr & MSR_TM)))
  80                         return 0;
  81                 /* mtmsrd doesn't change LE */
  82                 newmsr = (newmsr & ~MSR_LE) | (msr & MSR_LE);
  83                 newmsr = sanitize_msr(newmsr);
  84                 vcpu->arch.shregs.msr = newmsr;
  85                 return 1;
  86
  87         /* ignore bit 31, see comment above */
  88         case (PPC_INST_TSR & PO_XOP_OPCODE_MASK):
  89                 /* we know the MSR has the TS field = S (0b01) here */
  90                 msr = vcpu->arch.shregs.msr;
  91                 /* check for PR=1 and arch 2.06 bit set in PCR */
  92                 if ((msr & MSR_PR) && (vcpu->arch.vcore->pcr & PCR_ARCH_206))
  93                         return 0;
  94                 /* check for TM disabled in the HFSCR or MSR */
  95                 if (!(vcpu->arch.hfscr & HFSCR_TM) || !(msr & MSR_TM))
  96                         return 0;
  97                 /* L=1 => tresume => set TS to T (0b10) */
  98                 if (instr & (1 << 21))
  99                         vcpu->arch.shregs.msr = (msr & ~MSR_TS_MASK) | MSR_TS_T;
 100                 /* Set CR0 to 0b0010 */
 101                 vcpu->arch.regs.ccr = (vcpu->arch.regs.ccr & 0x0fffffff) |
 102                         0x20000000;
 103                 return 1;
 104         }
 105
 106         return 0;
 107 }
 108
 109 /*
 110  * This is called when we are returning to a guest in TM transactional
 111  * state.  We roll the guest state back to the checkpointed state.
 112  */
 113 void kvmhv_emulate_tm_rollback(struct kvm_vcpu *vcpu)
 114 {
 115         vcpu->arch.shregs.msr &= ~MSR_TS_MASK;  /* go to N state */
 116         vcpu->arch.regs.nip = vcpu->arch.tfhar;
 117         copy_from_checkpoint(vcpu);
 118         vcpu->arch.regs.ccr = (vcpu->arch.regs.ccr & 0x0fffffff) | 0xa0000000;
 119 }