KVM: MIPS: Use lddir/ldpte instructions to lookup gpa_mm.pgd

Loongson-3 can use lddir/ldpte instuctions to accelerate page table
walking, so use them to lookup gpa_mm.pgd.
Reviewed-by: Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>
Signed-off-by: Huacai Chen <chenhc@lemote.com>
Co-developed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Message-Id: <1590220602-3547-6-git-send-email-chenhc@lemote.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/mips/kvm/entry.c

@@ -56,6 +56,7 @@
 #define C0_BADVADDR	8, 0
 #define C0_BADINSTR	8, 1
 #define C0_BADINSTRP	8, 2
+#define C0_PGD		9, 7
 #define C0_ENTRYHI	10, 0
 #define C0_GUESTCTL1	10, 4
 #define C0_STATUS	12, 0
@@ -307,6 +308,9 @@ static void *kvm_mips_build_enter_guest(void *addr)
 
 #ifdef CONFIG_KVM_MIPS_VZ
 	/* Save normal linux process pgd (VZ guarantees pgd_reg is set) */
+	if (cpu_has_ldpte)
+		UASM_i_MFC0(&p, K0, C0_PWBASE);
+	else
 		UASM_i_MFC0(&p, K0, c0_kscratch(), pgd_reg);
 	UASM_i_SW(&p, K0, offsetof(struct kvm_vcpu_arch, host_pgd), K1);
 
@@ -469,8 +473,10 @@ void *kvm_mips_build_tlb_refill_exception(void *addr, void *handler)
 	u32 *p = addr;
 	struct uasm_label labels[2];
 	struct uasm_reloc relocs[2];
+#ifndef CONFIG_CPU_LOONGSON64
 	struct uasm_label *l = labels;
 	struct uasm_reloc *r = relocs;
+#endif
 
 	memset(labels, 0, sizeof(labels));
 	memset(relocs, 0, sizeof(relocs));
@@ -490,6 +496,16 @@ void *kvm_mips_build_tlb_refill_exception(void *addr, void *handler)
 	 */
 	preempt_disable();
 
+#ifdef CONFIG_CPU_LOONGSON64
+	UASM_i_MFC0(&p, K1, C0_PGD);
+	uasm_i_lddir(&p, K0, K1, 3);  /* global page dir */
+#ifndef __PAGETABLE_PMD_FOLDED
+	uasm_i_lddir(&p, K1, K0, 1);  /* middle page dir */
+#endif
+	uasm_i_ldpte(&p, K1, 0);      /* even */
+	uasm_i_ldpte(&p, K1, 1);      /* odd */
+	uasm_i_tlbwr(&p);
+#else
 	/*
 	 * Now for the actual refill bit. A lot of this can be common with the
 	 * Linux TLB refill handler, however we don't need to handle so many
@@ -512,6 +528,7 @@ void *kvm_mips_build_tlb_refill_exception(void *addr, void *handler)
 	build_get_ptep(&p, K0, K1);
 	build_update_entries(&p, K0, K1);
 	build_tlb_write_entry(&p, &l, &r, tlb_random);
+#endif
 
 	preempt_enable();