[PATCH V2 05/14] KVM: MIPS: Use lddir/ldpte instructions to lookup gpa_mm.pgd

Huacai Chen
2020-04-24T11:09:06Z

Loongson-3 can use lddir/ldpte instuctions to accelerate page table
walking, so use them to lookup gpa_mm.pgd.

Signed-off-by: Huacai Chen <chenhc@lemote.com>
Co-developed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
---
arch/mips/kvm/entry.c | 19 ++++++++++++++++++-
1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/arch/mips/kvm/entry.c b/arch/mips/kvm/entry.c
index 16e1c93..fd71694 100644
--- a/arch/mips/kvm/entry.c
+++ b/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
@@ -307,7 +308,10 @@ 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) */
- UASM_i_MFC0(&p, K0, c0_kscratch(), pgd_reg);
+ 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();

--
2.7.0