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author | James Hogan <james.hogan@imgtec.com> | 2016-09-10 23:56:46 +0100 |
---|---|---|
committer | James Hogan <james.hogan@imgtec.com> | 2017-02-03 15:20:53 +0000 |
commit | a7cfa7ac1236937dac431845596a39ba27364a00 (patch) | |
tree | 38a785ddc708a46158c709f726eac63dbe2f0a00 /arch/mips/kvm/entry.c | |
parent | 29b500b54ef379f1f3227b633dd477a4dd3cd62b (diff) | |
download | linux-stable-a7cfa7ac1236937dac431845596a39ba27364a00.tar.gz linux-stable-a7cfa7ac1236937dac431845596a39ba27364a00.tar.bz2 linux-stable-a7cfa7ac1236937dac431845596a39ba27364a00.zip |
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: James 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
Diffstat (limited to 'arch/mips/kvm/entry.c')
-rw-r--r-- | arch/mips/kvm/entry.c | 78 |
1 files changed, 78 insertions, 0 deletions
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). |