Commit a7cfa7ac authored by James Hogan's avatar James Hogan

KVM: MIPS: Add fast path TLB refill handler

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: 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
parent 29b500b5
...@@ -554,6 +554,7 @@ extern int kvm_mips_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu); ...@@ -554,6 +554,7 @@ extern int kvm_mips_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu);
/* Building of entry/exception code */ /* Building of entry/exception code */
int kvm_mips_entry_setup(void); int kvm_mips_entry_setup(void);
void *kvm_mips_build_vcpu_run(void *addr); 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_exception(void *addr, void *handler);
void *kvm_mips_build_exit(void *addr); void *kvm_mips_build_exit(void *addr);
......
...@@ -16,6 +16,7 @@ ...@@ -16,6 +16,7 @@
#include <asm/mmu_context.h> #include <asm/mmu_context.h>
#include <asm/msa.h> #include <asm/msa.h>
#include <asm/setup.h> #include <asm/setup.h>
#include <asm/tlbex.h>
#include <asm/uasm.h> #include <asm/uasm.h>
/* Register names */ /* Register names */
...@@ -122,6 +123,9 @@ int kvm_mips_entry_setup(void) ...@@ -122,6 +123,9 @@ int kvm_mips_entry_setup(void)
*/ */
unsigned int kscratch_mask = cpu_data[0].kscratch_mask; 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 */ /* Pick a scratch register for storing VCPU */
if (kscratch_mask) { if (kscratch_mask) {
scratch_vcpu[0] = c0_kscratch(); scratch_vcpu[0] = c0_kscratch();
...@@ -380,6 +384,80 @@ static void *kvm_mips_build_enter_guest(void *addr) ...@@ -380,6 +384,80 @@ static void *kvm_mips_build_enter_guest(void *addr)
return p; return p;
} }
/**
* 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. * kvm_mips_build_exception() - Assemble first level guest exception handler.
* @addr: Address to start writing code. * @addr: Address to start writing code.
......
...@@ -264,7 +264,7 @@ static inline void dump_handler(const char *symbol, void *start, void *end) ...@@ -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) struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm, unsigned int id)
{ {
int err, size; int err, size;
void *gebase, *p, *handler; void *gebase, *p, *handler, *refill_start, *refill_end;
int i; int i;
struct kvm_vcpu *vcpu = kzalloc(sizeof(struct kvm_vcpu), GFP_KERNEL); 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) ...@@ -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 */ /* Build guest exception vectors dynamically in unmapped memory */
handler = gebase + 0x2000; handler = gebase + 0x2000;
/* TLB Refill, EXL = 0 */ /* TLB refill */
kvm_mips_build_exception(gebase, handler); refill_start = gebase;
refill_end = kvm_mips_build_tlb_refill_exception(refill_start, handler);
/* General Exception Entry point */ /* General Exception Entry point */
kvm_mips_build_exception(gebase + 0x180, handler); kvm_mips_build_exception(gebase + 0x180, handler);
...@@ -344,6 +345,7 @@ struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm, unsigned int id) ...@@ -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("#include <asm/regdef.h>\n");
pr_debug("\n"); pr_debug("\n");
dump_handler("kvm_vcpu_run", vcpu->arch.vcpu_run, p); 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_gen_exc", gebase + 0x180, gebase + 0x200);
dump_handler("kvm_exit", gebase + 0x2000, vcpu->arch.vcpu_run); dump_handler("kvm_exit", gebase + 0x2000, vcpu->arch.vcpu_run);
......
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