KVM: MIPS: clean up redundant kvm_run parameters in assembly

In the current kvm version, 'kvm_run' has been included in the 'kvm_vcpu'
structure. For historical reasons, many kvm-related function parameters
retain the 'kvm_run' and 'kvm_vcpu' parameters at the same time. This
patch does a unified cleanup of these remaining redundant parameters.

Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
Reviewed-by: Huacai Chen <chenhc@lemote.com>
Tested-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Message-Id: <20200623131418.31473-6-tianjia.zhang@linux.alibaba.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/mips/include/asm/kvm_host.h

@@ -341,7 +341,7 @@ struct kvm_mips_tlb {
 #define KVM_MIPS_GUEST_TLB_SIZE	64
 struct kvm_vcpu_arch {
 	void *guest_ebase;
-	int (*vcpu_run)(struct kvm_run *run, struct kvm_vcpu *vcpu);
+	int (*vcpu_run)(struct kvm_vcpu *vcpu);
 
 	/* Host registers preserved across guest mode execution */
 	unsigned long host_stack;
@@ -852,7 +852,7 @@ int kvm_mips_emulation_init(struct kvm_mips_callbacks **install_callbacks);
 /* Debug: dump vcpu state */
 int kvm_arch_vcpu_dump_regs(struct kvm_vcpu *vcpu);
 
-extern int kvm_mips_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu);
+extern int kvm_mips_handle_exit(struct kvm_vcpu *vcpu);
 
 /* Building of entry/exception code */
 int kvm_mips_entry_setup(void);

arch/mips/kvm/entry.c

@@ -205,7 +205,7 @@ static inline void build_set_exc_base(u32 **p, unsigned int reg)
  * Assemble the start of the vcpu_run function to run a guest VCPU. The function
  * conforms to the following prototype:
  *
- * int vcpu_run(struct kvm_run *run, struct kvm_vcpu *vcpu);
+ * int vcpu_run(struct kvm_vcpu *vcpu);
  *
  * The exit from the guest and return to the caller is handled by the code
  * generated by kvm_mips_build_ret_to_host().
@@ -218,8 +218,7 @@ void *kvm_mips_build_vcpu_run(void *addr)
 	unsigned int i;
 
 	/*
-	 * A0: run
-	 * A1: vcpu
+	 * A0: vcpu
 	 */
 
 	/* k0/k1 not being used in host kernel context */
@@ -238,10 +237,10 @@ 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, A0, 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, A0, offsetof(struct kvm_vcpu, arch));
 
 	/*
 	 * Save the host stack to VCPU, used for exception processing
@@ -645,10 +644,7 @@ void *kvm_mips_build_exit(void *addr)
 	/* Now that context has been saved, we can use other registers */
 
 	/* Restore vcpu */
-	UASM_i_MFC0(&p, S1, scratch_vcpu[0], scratch_vcpu[1]);
-
-	/* Restore run (vcpu->run) */
-	UASM_i_LW(&p, S0, offsetof(struct kvm_vcpu, run), S1);
+	UASM_i_MFC0(&p, S0, scratch_vcpu[0], scratch_vcpu[1]);
 
 	/*
 	 * Save Host level EPC, BadVaddr and Cause to VCPU, useful to process
@@ -810,7 +806,6 @@ void *kvm_mips_build_exit(void *addr)
 	 * with this in the kernel
 	 */
 	uasm_i_move(&p, A0, S0);
-	uasm_i_move(&p, A1, S1);
 	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);
@@ -852,7 +847,7 @@ static void *kvm_mips_build_ret_from_exit(void *addr)
 	 * guest, reload k1
 	 */
 
-	uasm_i_move(&p, K1, S1);
+	uasm_i_move(&p, K1, S0);
 	UASM_i_ADDIU(&p, K1, K1, offsetof(struct kvm_vcpu, arch));
 
 	/*
@@ -886,8 +881,8 @@ 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]);
+	/* Put the saved pointer to vcpu (s0) back into the scratch register */
+	UASM_i_MTC0(&p, S0, 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);

arch/mips/kvm/mips.c

@@ -1199,8 +1199,9 @@ static void kvm_mips_set_c0_status(void)
 /*
  * Return value is in the form (errcode<<2 | RESUME_FLAG_HOST | RESUME_FLAG_NV)
  */
-int kvm_mips_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu)
+int kvm_mips_handle_exit(struct kvm_vcpu *vcpu)
 {
+	struct kvm_run *run = vcpu->run;
 	u32 cause = vcpu->arch.host_cp0_cause;
 	u32 exccode = (cause >> CAUSEB_EXCCODE) & 0x1f;
 	u32 __user *opc = (u32 __user *) vcpu->arch.pc;

arch/mips/kvm/trap_emul.c

@@ -1241,7 +1241,7 @@ static int kvm_trap_emul_vcpu_run(struct kvm_vcpu *vcpu)
 	 */
 	kvm_mips_suspend_mm(cpu);
 
-	r = vcpu->arch.vcpu_run(vcpu->run, vcpu);
+	r = vcpu->arch.vcpu_run(vcpu);
 
 	/* We may have migrated while handling guest exits */
 	cpu = smp_processor_id();

arch/mips/kvm/vz.c

@@ -3266,7 +3266,7 @@ static int kvm_vz_vcpu_run(struct kvm_vcpu *vcpu)
 	kvm_vz_vcpu_load_tlb(vcpu, cpu);
 	kvm_vz_vcpu_load_wired(vcpu);
 
-	r = vcpu->arch.vcpu_run(vcpu->run, vcpu);
+	r = vcpu->arch.vcpu_run(vcpu);
 
 	kvm_vz_vcpu_save_wired(vcpu);