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Commit 420ea09b authored by James Hogan's avatar James Hogan
Browse files

KVM: MIPS/T&E: Abstract bad access handling 



Abstract the handling of bad guest loads and stores which may need to
trigger an MMIO, so that the same code can be used in a later patch for
guest KSeg0 addresses (TLB exception handling) as well as for host KSeg1
addresses (existing address error exception and TLB exception handling).

We now use kvm_mips_emulate_store() and kvm_mips_emulate_load() directly
rather than the more generic kvm_mips_emulate_inst(), as there is no
need to expose emulation of any other instructions.

Signed-off-by: default avatarJames 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: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
parent 577ed7f7

arch/mips/kvm/trap_emul.c

+72 −47
Original line number Diff line number Diff line
@@ -85,6 +85,75 @@ static int kvm_trap_emul_handle_cop_unusable(struct kvm_vcpu *vcpu) 
	return ret;

}



static int kvm_mips_bad_load(u32 cause, u32 *opc, struct kvm_run *run,

			     struct kvm_vcpu *vcpu)

{

	enum emulation_result er;

	union mips_instruction inst;

	int err;



	/* A code fetch fault doesn't count as an MMIO */

	if (kvm_is_ifetch_fault(&vcpu->arch)) {

		run->exit_reason = KVM_EXIT_INTERNAL_ERROR;

		return RESUME_HOST;

	}



	/* Fetch the instruction. */

	if (cause & CAUSEF_BD)

		opc += 1;

	err = kvm_get_badinstr(opc, vcpu, &inst.word);

	if (err) {

		run->exit_reason = KVM_EXIT_INTERNAL_ERROR;

		return RESUME_HOST;

	}



	/* Emulate the load */

	er = kvm_mips_emulate_load(inst, cause, run, vcpu);

	if (er == EMULATE_FAIL) {

		kvm_err("Emulate load from MMIO space failed\n");

		run->exit_reason = KVM_EXIT_INTERNAL_ERROR;

	} else {

		run->exit_reason = KVM_EXIT_MMIO;

	}

	return RESUME_HOST;

}



static int kvm_mips_bad_store(u32 cause, u32 *opc, struct kvm_run *run,

			      struct kvm_vcpu *vcpu)

{

	enum emulation_result er;

	union mips_instruction inst;

	int err;



	/* Fetch the instruction. */

	if (cause & CAUSEF_BD)

		opc += 1;

	err = kvm_get_badinstr(opc, vcpu, &inst.word);

	if (err) {

		run->exit_reason = KVM_EXIT_INTERNAL_ERROR;

		return RESUME_HOST;

	}



	/* Emulate the store */

	er = kvm_mips_emulate_store(inst, cause, run, vcpu);

	if (er == EMULATE_FAIL) {

		kvm_err("Emulate store to MMIO space failed\n");

		run->exit_reason = KVM_EXIT_INTERNAL_ERROR;

	} else {

		run->exit_reason = KVM_EXIT_MMIO;

	}

	return RESUME_HOST;

}



static int kvm_mips_bad_access(u32 cause, u32 *opc, struct kvm_run *run,

			       struct kvm_vcpu *vcpu, bool store)

{

	if (store)

		return kvm_mips_bad_store(cause, opc, run, vcpu);

	else

		return kvm_mips_bad_load(cause, opc, run, vcpu);

}



static int kvm_trap_emul_handle_tlb_mod(struct kvm_vcpu *vcpu)

{

	struct kvm_run *run = vcpu->run;
@@ -178,28 +247,11 @@ static int kvm_trap_emul_handle_tlb_miss(struct kvm_vcpu *vcpu, bool store) 
		}

	} else if (KVM_GUEST_KERNEL_MODE(vcpu)

		   && (KSEGX(badvaddr) == CKSEG0 || KSEGX(badvaddr) == CKSEG1)) {

		/* A code fetch fault doesn't count as an MMIO */

		if (!store && kvm_is_ifetch_fault(&vcpu->arch)) {

			run->exit_reason = KVM_EXIT_INTERNAL_ERROR;

			return RESUME_HOST;

		}



		/*

		 * With EVA we may get a TLB exception instead of an address

		 * error when the guest performs MMIO to KSeg1 addresses.

		 */

		kvm_debug("Emulate %s MMIO space\n",

			  store ? "Store to" : "Load from");

		er = kvm_mips_emulate_inst(cause, opc, run, vcpu);

		if (er == EMULATE_FAIL) {

			kvm_err("Emulate %s MMIO space failed\n",

				store ? "Store to" : "Load from");

			run->exit_reason = KVM_EXIT_INTERNAL_ERROR;

			ret = RESUME_HOST;

		} else {

			run->exit_reason = KVM_EXIT_MMIO;

			ret = RESUME_HOST;

		}

		ret = kvm_mips_bad_access(cause, opc, run, vcpu, store);

	} else {

		kvm_err("Illegal TLB %s fault address , cause %#x, PC: %p, BadVaddr: %#lx\n",

			store ? "ST" : "LD", cause, opc, badvaddr);
@@ -227,21 +279,11 @@ static int kvm_trap_emul_handle_addr_err_st(struct kvm_vcpu *vcpu) 
	u32 __user *opc = (u32 __user *) vcpu->arch.pc;

	unsigned long badvaddr = vcpu->arch.host_cp0_badvaddr;

	u32 cause = vcpu->arch.host_cp0_cause;

	enum emulation_result er = EMULATE_DONE;

	int ret = RESUME_GUEST;



	if (KVM_GUEST_KERNEL_MODE(vcpu)

	    && (KSEGX(badvaddr) == CKSEG0 || KSEGX(badvaddr) == CKSEG1)) {

		kvm_debug("Emulate Store to MMIO space\n");

		er = kvm_mips_emulate_inst(cause, opc, run, vcpu);

		if (er == EMULATE_FAIL) {

			kvm_err("Emulate Store to MMIO space failed\n");

			run->exit_reason = KVM_EXIT_INTERNAL_ERROR;

			ret = RESUME_HOST;

		} else {

			run->exit_reason = KVM_EXIT_MMIO;

			ret = RESUME_HOST;

		}

		ret = kvm_mips_bad_store(cause, opc, run, vcpu);

	} else {

		kvm_err("Address Error (STORE): cause %#x, PC: %p, BadVaddr: %#lx\n",

			cause, opc, badvaddr);
@@ -257,32 +299,15 @@ static int kvm_trap_emul_handle_addr_err_ld(struct kvm_vcpu *vcpu) 
	u32 __user *opc = (u32 __user *) vcpu->arch.pc;

	unsigned long badvaddr = vcpu->arch.host_cp0_badvaddr;

	u32 cause = vcpu->arch.host_cp0_cause;

	enum emulation_result er = EMULATE_DONE;

	int ret = RESUME_GUEST;



	if (KSEGX(badvaddr) == CKSEG0 || KSEGX(badvaddr) == CKSEG1) {

		/* A code fetch fault doesn't count as an MMIO */

		if (kvm_is_ifetch_fault(&vcpu->arch)) {

			run->exit_reason = KVM_EXIT_INTERNAL_ERROR;

			return RESUME_HOST;

		}



		kvm_debug("Emulate Load from MMIO space @ %#lx\n", badvaddr);

		er = kvm_mips_emulate_inst(cause, opc, run, vcpu);

		if (er == EMULATE_FAIL) {

			kvm_err("Emulate Load from MMIO space failed\n");

			run->exit_reason = KVM_EXIT_INTERNAL_ERROR;

			ret = RESUME_HOST;

		} else {

			run->exit_reason = KVM_EXIT_MMIO;

			ret = RESUME_HOST;

		}

		ret = kvm_mips_bad_load(cause, opc, run, vcpu);

	} else {

		kvm_err("Address Error (LOAD): cause %#x, PC: %p, BadVaddr: %#lx\n",

			cause, opc, badvaddr);

		run->exit_reason = KVM_EXIT_INTERNAL_ERROR;

		ret = RESUME_HOST;

		er = EMULATE_FAIL;

	}

	return ret;

}