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Commit 70e92c7e authored by James Hogan's avatar James Hogan Committed by Paolo Bonzini
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MIPS: KVM: Don't save/restore lo/hi for r6 



MIPSr6 doesn't have lo/hi registers, so don't bother saving or
restoring them, and don't expose them to userland with the KVM ioctl
interface either.

In fact the lo/hi registers aren't callee saved in the MIPS ABIs anyway,
so there is no need to preserve the host lo/hi values at all when
transitioning to and from the guest (which happens via a function call).

Signed-off-by: default avatarJames Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim KrÄmář <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent d85ebff0

arch/mips/kvm/entry.c

+4 −12
Original line number Diff line number Diff line
@@ -178,12 +178,6 @@ void *kvm_mips_build_vcpu_run(void *addr) 
		UASM_i_SW(&p, i, offsetof(struct pt_regs, regs[i]), K1);

	}



	/* Save hi/lo */

	uasm_i_mflo(&p, V0);

	UASM_i_SW(&p, V0, offsetof(struct pt_regs, lo), K1);

	uasm_i_mfhi(&p, V1);

	UASM_i_SW(&p, V1, offsetof(struct pt_regs, hi), K1);



	/* Save host status */

	uasm_i_mfc0(&p, V0, C0_STATUS);

	UASM_i_SW(&p, V0, offsetof(struct pt_regs, cp0_status), K1);
@@ -307,12 +301,14 @@ static void *kvm_mips_build_enter_guest(void *addr) 
		UASM_i_LW(&p, i, offsetof(struct kvm_vcpu_arch, gprs[i]), K1);

	}



#ifndef CONFIG_CPU_MIPSR6

	/* Restore hi/lo */

	UASM_i_LW(&p, K0, offsetof(struct kvm_vcpu_arch, hi), K1);

	uasm_i_mthi(&p, K0);



	UASM_i_LW(&p, K0, offsetof(struct kvm_vcpu_arch, lo), K1);

	uasm_i_mtlo(&p, K0);

#endif



	/* Restore the guest's k0/k1 registers */

	UASM_i_LW(&p, K0, offsetof(struct kvm_vcpu_arch, gprs[K0]), K1);
@@ -408,12 +404,14 @@ void *kvm_mips_build_exit(void *addr) 
		UASM_i_SW(&p, i, offsetof(struct kvm_vcpu_arch, gprs[i]), K1);

	}



#ifndef CONFIG_CPU_MIPSR6

	/* We need to save hi/lo and restore them on the way out */

	uasm_i_mfhi(&p, T0);

	UASM_i_SW(&p, T0, offsetof(struct kvm_vcpu_arch, hi), K1);



	uasm_i_mflo(&p, T0);

	UASM_i_SW(&p, T0, offsetof(struct kvm_vcpu_arch, lo), K1);

#endif



	/* Finally save guest k1 to VCPU */

	uasm_i_ehb(&p);
@@ -663,12 +661,6 @@ static void *kvm_mips_build_ret_to_host(void *addr) 
		UASM_i_LW(&p, i, offsetof(struct pt_regs, regs[i]), K1);

	}



	UASM_i_LW(&p, K0, offsetof(struct pt_regs, hi), K1);

	uasm_i_mthi(&p, K0);



	UASM_i_LW(&p, K0, offsetof(struct pt_regs, lo), K1);

	uasm_i_mtlo(&p, K0);



	/* Restore RDHWR access */

	UASM_i_LA_mostly(&p, K0, (long)&hwrena);

	uasm_i_lw(&p, K0, uasm_rel_lo((long)&hwrena), K0);

arch/mips/kvm/mips.c

+6 −0
Original line number Diff line number Diff line
@@ -521,8 +521,10 @@ static u64 kvm_mips_get_one_regs[] = { 
	KVM_REG_MIPS_R30,

	KVM_REG_MIPS_R31,



#ifndef CONFIG_CPU_MIPSR6

	KVM_REG_MIPS_HI,

	KVM_REG_MIPS_LO,

#endif

	KVM_REG_MIPS_PC,



	KVM_REG_MIPS_CP0_INDEX,
@@ -666,12 +668,14 @@ static int kvm_mips_get_reg(struct kvm_vcpu *vcpu, 
	case KVM_REG_MIPS_R0 ... KVM_REG_MIPS_R31:

		v = (long)vcpu->arch.gprs[reg->id - KVM_REG_MIPS_R0];

		break;

#ifndef CONFIG_CPU_MIPSR6

	case KVM_REG_MIPS_HI:

		v = (long)vcpu->arch.hi;

		break;

	case KVM_REG_MIPS_LO:

		v = (long)vcpu->arch.lo;

		break;

#endif

	case KVM_REG_MIPS_PC:

		v = (long)vcpu->arch.pc;

		break;
@@ -887,12 +891,14 @@ static int kvm_mips_set_reg(struct kvm_vcpu *vcpu, 
	case KVM_REG_MIPS_R1 ... KVM_REG_MIPS_R31:

		vcpu->arch.gprs[reg->id - KVM_REG_MIPS_R0] = v;

		break;

#ifndef CONFIG_CPU_MIPSR6

	case KVM_REG_MIPS_HI:

		vcpu->arch.hi = v;

		break;

	case KVM_REG_MIPS_LO:

		vcpu->arch.lo = v;

		break;

#endif

	case KVM_REG_MIPS_PC:

		vcpu->arch.pc = v;

		break;