Commit e41637d8 authored by James Hogan's avatar James Hogan Committed by Paolo Bonzini
Browse files

MIPS: KVM: Make entry code MIPS64 friendly 



The MIPS KVM entry code (originally kvm_locore.S, later locore.S, and
now entry.c) has never quite been right when built for 64-bit, using
32-bit instructions when 64-bit instructions were needed for handling
64-bit registers and pointers. Fix several cases of this now.

The changes roughly fall into the following categories.

- COP0 scratch registers contain guest register values and the VCPU
  pointer, and are themselves full width. Similarly CP0_EPC and
  CP0_BadVAddr registers are full width (even though technically we
  don't support 64-bit guest address spaces with trap & emulate KVM).
  Use MFC0/MTC0 for accessing them.

- Handling of stack pointers and the VCPU pointer must match the pointer
  size of the kernel ABI (always o32 or n64), so use ADDIU.

- The CPU number in thread_info, and the guest_{user,kernel}_asid arrays
  in kvm_vcpu_arch are all 32 bit integers, so use lw (instead of LW) to
  load them.

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
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 28cc5bd5

arch/mips/kvm/entry.c

+24 −24
Original line number Diff line number Diff line
@@ -120,12 +120,12 @@ static void kvm_mips_build_save_scratch(u32 **p, unsigned int tmp, 
					unsigned int frame)

{

	/* Save the VCPU scratch register value in cp0_epc of the stack frame */

	uasm_i_mfc0(p, tmp, scratch_vcpu[0], scratch_vcpu[1]);

	UASM_i_MFC0(p, tmp, scratch_vcpu[0], scratch_vcpu[1]);

	UASM_i_SW(p, tmp, offsetof(struct pt_regs, cp0_epc), frame);



	/* Save the temp scratch register value in cp0_cause of stack frame */

	if (scratch_tmp[0] == 31) {

		uasm_i_mfc0(p, tmp, scratch_tmp[0], scratch_tmp[1]);

		UASM_i_MFC0(p, tmp, scratch_tmp[0], scratch_tmp[1]);

		UASM_i_SW(p, tmp, offsetof(struct pt_regs, cp0_cause), frame);

	}

}
@@ -138,11 +138,11 @@ static void kvm_mips_build_restore_scratch(u32 **p, unsigned int tmp, 
	 * kvm_mips_build_save_scratch().

	 */

	UASM_i_LW(p, tmp, offsetof(struct pt_regs, cp0_epc), frame);

	uasm_i_mtc0(p, tmp, scratch_vcpu[0], scratch_vcpu[1]);

	UASM_i_MTC0(p, tmp, scratch_vcpu[0], scratch_vcpu[1]);



	if (scratch_tmp[0] == 31) {

		UASM_i_LW(p, tmp, offsetof(struct pt_regs, cp0_cause), frame);

		uasm_i_mtc0(p, tmp, scratch_tmp[0], scratch_tmp[1]);

		UASM_i_MTC0(p, tmp, scratch_tmp[0], scratch_tmp[1]);

	}

}
@@ -171,7 +171,7 @@ void *kvm_mips_build_vcpu_run(void *addr) 
	 */



	/* k0/k1 not being used in host kernel context */

	uasm_i_addiu(&p, K1, SP, -(int)sizeof(struct pt_regs));

	UASM_i_ADDIU(&p, K1, SP, -(int)sizeof(struct pt_regs));

	for (i = 16; i < 32; ++i) {

		if (i == 24)

			i = 28;
@@ -186,10 +186,10 @@ void *kvm_mips_build_vcpu_run(void *addr) 
	kvm_mips_build_save_scratch(&p, V1, K1);



	/* VCPU scratch register has pointer to vcpu */

	uasm_i_mtc0(&p, A1, scratch_vcpu[0], scratch_vcpu[1]);

	UASM_i_MTC0(&p, A1, scratch_vcpu[0], scratch_vcpu[1]);



	/* Offset into vcpu->arch */

	uasm_i_addiu(&p, K1, A1, offsetof(struct kvm_vcpu, arch));

	UASM_i_ADDIU(&p, K1, A1, offsetof(struct kvm_vcpu, arch));



	/*

	 * Save the host stack to VCPU, used for exception processing
@@ -252,7 +252,7 @@ static void *kvm_mips_build_enter_guest(void *addr) 


	/* Set Guest EPC */

	UASM_i_LW(&p, T0, offsetof(struct kvm_vcpu_arch, pc), K1);

	uasm_i_mtc0(&p, T0, C0_EPC);

	UASM_i_MTC0(&p, T0, C0_EPC);



	/* Set the ASID for the Guest Kernel */

	UASM_i_LW(&p, T0, offsetof(struct kvm_vcpu_arch, cop0), K1);
@@ -261,20 +261,20 @@ static void *kvm_mips_build_enter_guest(void *addr) 
	uasm_i_andi(&p, T0, T0, KSU_USER | ST0_ERL | ST0_EXL);

	uasm_i_xori(&p, T0, T0, KSU_USER);

	uasm_il_bnez(&p, &r, T0, label_kernel_asid);

	 uasm_i_addiu(&p, T1, K1,

	 UASM_i_ADDIU(&p, T1, K1,

		      offsetof(struct kvm_vcpu_arch, guest_kernel_asid));

	/* else user */

	uasm_i_addiu(&p, T1, K1,

	UASM_i_ADDIU(&p, T1, K1,

		     offsetof(struct kvm_vcpu_arch, guest_user_asid));

	uasm_l_kernel_asid(&l, p);



	/* t1: contains the base of the ASID array, need to get the cpu id  */

	/* smp_processor_id */

	UASM_i_LW(&p, T2, offsetof(struct thread_info, cpu), GP);

	uasm_i_lw(&p, T2, offsetof(struct thread_info, cpu), GP);

	/* x4 */

	uasm_i_sll(&p, T2, T2, 2);

	UASM_i_ADDU(&p, T3, T1, T2);

	UASM_i_LW(&p, K0, 0, T3);

	uasm_i_lw(&p, K0, 0, T3);

#ifdef CONFIG_MIPS_ASID_BITS_VARIABLE

	/* x sizeof(struct cpuinfo_mips)/4 */

	uasm_i_addiu(&p, T3, ZERO, sizeof(struct cpuinfo_mips)/4);
@@ -344,11 +344,11 @@ void *kvm_mips_build_exception(void *addr, void *handler) 
	memset(relocs, 0, sizeof(relocs));



	/* Save guest k1 into scratch register */

	uasm_i_mtc0(&p, K1, scratch_tmp[0], scratch_tmp[1]);

	UASM_i_MTC0(&p, K1, scratch_tmp[0], scratch_tmp[1]);



	/* Get the VCPU pointer from the VCPU scratch register */

	uasm_i_mfc0(&p, K1, scratch_vcpu[0], scratch_vcpu[1]);

	uasm_i_addiu(&p, K1, K1, offsetof(struct kvm_vcpu, arch));

	UASM_i_MFC0(&p, K1, scratch_vcpu[0], scratch_vcpu[1]);

	UASM_i_ADDIU(&p, K1, K1, offsetof(struct kvm_vcpu, arch));



	/* Save guest k0 into VCPU structure */

	UASM_i_SW(&p, K0, offsetof(struct kvm_vcpu_arch, gprs[K0]), K1);
@@ -415,13 +415,13 @@ void *kvm_mips_build_exit(void *addr) 


	/* Finally save guest k1 to VCPU */

	uasm_i_ehb(&p);

	uasm_i_mfc0(&p, T0, scratch_tmp[0], scratch_tmp[1]);

	UASM_i_MFC0(&p, T0, scratch_tmp[0], scratch_tmp[1]);

	UASM_i_SW(&p, T0, offsetof(struct kvm_vcpu_arch, gprs[K1]), K1);



	/* Now that context has been saved, we can use other registers */



	/* Restore vcpu */

	uasm_i_mfc0(&p, A1, scratch_vcpu[0], scratch_vcpu[1]);

	UASM_i_MFC0(&p, A1, scratch_vcpu[0], scratch_vcpu[1]);

	uasm_i_move(&p, S1, A1);



	/* Restore run (vcpu->run) */
@@ -433,10 +433,10 @@ void *kvm_mips_build_exit(void *addr) 
	 * Save Host level EPC, BadVaddr and Cause to VCPU, useful to process

	 * the exception

	 */

	uasm_i_mfc0(&p, K0, C0_EPC);

	UASM_i_MFC0(&p, K0, C0_EPC);

	UASM_i_SW(&p, K0, offsetof(struct kvm_vcpu_arch, pc), K1);



	uasm_i_mfc0(&p, K0, C0_BADVADDR);

	UASM_i_MFC0(&p, K0, C0_BADVADDR);

	UASM_i_SW(&p, K0, offsetof(struct kvm_vcpu_arch, host_cp0_badvaddr),

		  K1);
@@ -506,7 +506,7 @@ void *kvm_mips_build_exit(void *addr) 
	UASM_i_LW(&p, SP, offsetof(struct kvm_vcpu_arch, host_stack), K1);



	/* Saved host state */

	uasm_i_addiu(&p, SP, SP, -(int)sizeof(struct pt_regs));

	UASM_i_ADDIU(&p, SP, SP, -(int)sizeof(struct pt_regs));



	/*

	 * XXXKYMA do we need to load the host ASID, maybe not because the
@@ -529,7 +529,7 @@ void *kvm_mips_build_exit(void *addr) 
	 */

	UASM_i_LA(&p, T9, (unsigned long)kvm_mips_handle_exit);

	uasm_i_jalr(&p, RA, T9);

	 uasm_i_addiu(&p, SP, SP, -CALLFRAME_SIZ);

	 UASM_i_ADDIU(&p, SP, SP, -CALLFRAME_SIZ);



	uasm_resolve_relocs(relocs, labels);
@@ -569,7 +569,7 @@ static void *kvm_mips_build_ret_from_exit(void *addr) 
	 */



	uasm_i_move(&p, K1, S1);

	uasm_i_addiu(&p, K1, K1, offsetof(struct kvm_vcpu, arch));

	UASM_i_ADDIU(&p, K1, K1, offsetof(struct kvm_vcpu, arch));



	/*

	 * Check return value, should tell us if we are returning to the
@@ -603,7 +603,7 @@ static void *kvm_mips_build_ret_to_guest(void *addr) 
	u32 *p = addr;



	/* Put the saved pointer to vcpu (s1) back into the scratch register */

	uasm_i_mtc0(&p, S1, scratch_vcpu[0], scratch_vcpu[1]);

	UASM_i_MTC0(&p, S1, scratch_vcpu[0], scratch_vcpu[1]);



	/* Load up the Guest EBASE to minimize the window where BEV is set */

	UASM_i_LW(&p, T0, offsetof(struct kvm_vcpu_arch, guest_ebase), K1);
@@ -645,7 +645,7 @@ static void *kvm_mips_build_ret_to_host(void *addr) 


	/* EBASE is already pointing to Linux */

	UASM_i_LW(&p, K1, offsetof(struct kvm_vcpu_arch, host_stack), K1);

	uasm_i_addiu(&p, K1, K1, -(int)sizeof(struct pt_regs));

	UASM_i_ADDIU(&p, K1, K1, -(int)sizeof(struct pt_regs));



	/*

	 * r2/v0 is the return code, shift it down by 2 (arithmetic)

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