MIPS: KVM: Don't unwind PC when emulating CACHE
When a CACHE instruction is emulated by kvm_mips_emulate_cache(), the PC is first updated to point to the next instruction, and afterwards it falls through the "dont_update_pc" label, which rewinds the PC back to its original address. This works when dynamic translation of emulated instructions is enabled, since the CACHE instruction is replaced with a SYNCI which works without trapping, however when dynamic translation is disabled the guest hangs on CACHE instructions as they always trap and are never stepped over. Roughly swap the meanings of the "done" and "dont_update_pc" to match kvm_mips_emulate_CP0(), so that "done" will roll back the PC on failure, and "dont_update_pc" won't change PC at all (for the sake of exceptions that have already modified the PC). Signed-off-by: James Hogan <james.hogan@imgtec.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: kvm@vger.kernel.org Cc: linux-mips@linux-mips.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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@ -1666,7 +1666,7 @@ enum emulation_result kvm_mips_emulate_cache(uint32_t inst, uint32_t *opc,
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cache, op, base, arch->gprs[base], offset);
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er = EMULATE_FAIL;
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preempt_enable();
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goto dont_update_pc;
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goto done;
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}
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@ -1694,16 +1694,20 @@ skip_fault:
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kvm_err("NO-OP CACHE (cache: %#x, op: %#x, base[%d]: %#lx, offset: %#x\n",
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cache, op, base, arch->gprs[base], offset);
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er = EMULATE_FAIL;
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preempt_enable();
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goto dont_update_pc;
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}
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preempt_enable();
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done:
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/* Rollback PC only if emulation was unsuccessful */
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if (er == EMULATE_FAIL)
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vcpu->arch.pc = curr_pc;
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dont_update_pc:
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/* Rollback PC */
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vcpu->arch.pc = curr_pc;
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done:
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/*
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* This is for exceptions whose emulation updates the PC, so do not
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* overwrite the PC under any circumstances
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*/
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return er;
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}
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