Use functions from the general MIPS TLB exception vector generation code
(tlbex.c) to construct a fast path TLB refill handler similar to the
general one, but cut down and capable of preserving K0 and K1.
Signed-off-by: James Hogan <james.hogan@xxxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: "Radim Krčmář" <rkrcmar@xxxxxxxxxx>
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: linux-mips@xxxxxxxxxxxxxx
Cc: kvm@xxxxxxxxxxxxxxx
---
arch/mips/include/asm/kvm_host.h | 1 +-
arch/mips/kvm/entry.c | 78 +++++++++++++++++++++++++++++++++-
arch/mips/kvm/mips.c | 8 +--
3 files changed, 84 insertions(+), 3 deletions(-)
diff --git a/arch/mips/include/asm/kvm_host.h b/arch/mips/include/asm/kvm_host.h
index 8c4a33e9687d..7bf8ee8bc01d 100644
--- a/arch/mips/include/asm/kvm_host.h
+++ b/arch/mips/include/asm/kvm_host.h
@@ -554,6 +554,7 @@ extern int kvm_mips_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu);
/* Building of entry/exception code */
int kvm_mips_entry_setup(void);
void *kvm_mips_build_vcpu_run(void *addr);
+void *kvm_mips_build_tlb_refill_exception(void *addr, void *handler);
void *kvm_mips_build_exception(void *addr, void *handler);
void *kvm_mips_build_exit(void *addr);
diff --git a/arch/mips/kvm/entry.c b/arch/mips/kvm/entry.c
index 7424d3d566ff..1ae33e0e675c 100644
--- a/arch/mips/kvm/entry.c
+++ b/arch/mips/kvm/entry.c
@@ -16,6 +16,7 @@
#include <asm/mmu_context.h>
#include <asm/msa.h>
#include <asm/setup.h>
+#include <asm/tlbex.h>
#include <asm/uasm.h>
/* Register names */
@@ -122,6 +123,9 @@ int kvm_mips_entry_setup(void)
*/
unsigned int kscratch_mask = cpu_data[0].kscratch_mask;
+ if (pgd_reg != -1)
+ kscratch_mask &= ~BIT(pgd_reg);
+
/* Pick a scratch register for storing VCPU */
if (kscratch_mask) {
scratch_vcpu[0] = c0_kscratch();
@@ -381,6 +385,80 @@ static void *kvm_mips_build_enter_guest(void *addr)
}
/**
+ * kvm_mips_build_tlb_refill_exception() - Assemble TLB refill handler.
+ * @addr: Address to start writing code.
+ * @handler: Address of common handler (within range of @addr).
+ *
+ * Assemble TLB refill exception fast path handler for guest execution.
+ *
+ * Returns: Next address after end of written function.
+ */
+void *kvm_mips_build_tlb_refill_exception(void *addr, void *handler)
+{
+ u32 *p = addr;
+ struct uasm_label labels[2];
+ struct uasm_reloc relocs[2];
+ struct uasm_label *l = labels;
+ struct uasm_reloc *r = relocs;
+
+ memset(labels, 0, sizeof(labels));
+ memset(relocs, 0, sizeof(relocs));
+
+ /* Save guest k1 into scratch register */
+ 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]);
+
+ /* Save guest k0 into VCPU structure */
+ UASM_i_SW(&p, K0, offsetof(struct kvm_vcpu, arch.gprs[K0]), K1);
+
+ /*
+ * Some of the common tlbex code uses current_cpu_type(). For KVM we
+ * assume symmetry and just disable preemption to silence the warning.
+ */
+ preempt_disable();
+
+ /*
+ * 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
+ * cases. We only need to handle user mode refills, and user mode runs
+ * with 32-bit addressing.
+ *
+ * Therefore the branch to label_vmalloc generated by build_get_pmde64()
+ * that isn't resolved should never actually get taken and is harmless
+ * to leave in place for now.
+ */
+
+#ifdef CONFIG_64BIT
+ build_get_pmde64(&p, &l, &r, K0, K1); /* get pmd in K1 */
+#else
+ build_get_pgde32(&p, K0, K1); /* get pgd in K1 */
+#endif
+
+ /* we don't support huge pages yet */
+
+ build_get_ptep(&p, K0, K1);
+ build_update_entries(&p, K0, K1);
+ build_tlb_write_entry(&p, &l, &r, tlb_random);
+
+ preempt_enable();
+
+ /* Get the VCPU pointer from the VCPU scratch register again */
+ UASM_i_MFC0(&p, K1, scratch_vcpu[0], scratch_vcpu[1]);
+
+ /* Restore the guest's k0/k1 registers */
+ UASM_i_LW(&p, K0, offsetof(struct kvm_vcpu, arch.gprs[K0]), K1);
+ uasm_i_ehb(&p);
+ UASM_i_MFC0(&p, K1, scratch_tmp[0], scratch_tmp[1]);
+
+ /* Jump to guest */
+ uasm_i_eret(&p);
+
+ return p;
+}
+
+/**
* kvm_mips_build_exception() - Assemble first level guest exception handler.
* @addr: Address to start writing code.
* @handler: Address of common handler (within range of @addr).
diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
index 39792ec73a6d..3cf720790ce6 100644
--- a/arch/mips/kvm/mips.c
+++ b/arch/mips/kvm/mips.c
@@ -264,7 +264,7 @@ static inline void dump_handler(const char *symbol, void *start, void *end)
struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm, unsigned int id)
{
int err, size;
- void *gebase, *p, *handler;
+ void *gebase, *p, *handler, *refill_start, *refill_end;
int i;
struct kvm_vcpu *vcpu = kzalloc(sizeof(struct kvm_vcpu), GFP_KERNEL);
@@ -317,8 +317,9 @@ struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm, unsigned int id)
/* Build guest exception vectors dynamically in unmapped memory */
handler = gebase + 0x2000;
- /* TLB Refill, EXL = 0 */
- kvm_mips_build_exception(gebase, handler);
+ /* TLB refill */
+ refill_start = gebase;
+ refill_end = kvm_mips_build_tlb_refill_exception(refill_start, handler);
/* General Exception Entry point */
kvm_mips_build_exception(gebase + 0x180, handler);
@@ -344,6 +345,7 @@ struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm, unsigned int id)
pr_debug("#include <asm/regdef.h>\n");
pr_debug("\n");
dump_handler("kvm_vcpu_run", vcpu->arch.vcpu_run, p);
+ dump_handler("kvm_tlb_refill", refill_start, refill_end);
dump_handler("kvm_gen_exc", gebase + 0x180, gebase + 0x200);
dump_handler("kvm_exit", gebase + 0x2000, vcpu->arch.vcpu_run);
--
git-series 0.8.10
