KVM: arm64: Convert lazy FPSIMD context switch trap to C

To make the lazy FPSIMD context switch trap code easier to hack on,
this patch converts it to C.

This is not amazingly efficient, but the trap should typically only
be taken once per host context switch.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

diff --git a/arch/arm64/kvm/hyp/entry.S b/arch/arm64/kvm/hyp/entry.S
index e41a161d313a6f93ab92690bce5053b7f2b952c8..40f349bc1079fb1d5beb08f4a678f3815c33f855 100644 (file)
--- a/arch/arm64/kvm/hyp/entry.S
+++ b/arch/arm64/kvm/hyp/entry.S
@@ -172,40 +172,27 @@ ENTRY(__fpsimd_guest_restore)
        // x1: vcpu
        // x2-x29,lr: vcpu regs
        // vcpu x0-x1 on the stack
-       stp     x2, x3, [sp, #-16]!
-       stp     x4, lr, [sp, #-16]!
-
-alternative_if_not ARM64_HAS_VIRT_HOST_EXTN
-       mrs     x2, cptr_el2
-       bic     x2, x2, #CPTR_EL2_TFP
-       msr     cptr_el2, x2
-alternative_else
-       mrs     x2, cpacr_el1
-       orr     x2, x2, #CPACR_EL1_FPEN
-       msr     cpacr_el1, x2
-alternative_endif
-       isb
-
-       mov     x3, x1
-
-       ldr     x0, [x3, #VCPU_HOST_CONTEXT]
-       kern_hyp_va x0
-       add     x0, x0, #CPU_GP_REG_OFFSET(CPU_FP_REGS)
-       bl      __fpsimd_save_state
-
-       add     x2, x3, #VCPU_CONTEXT
-       add     x0, x2, #CPU_GP_REG_OFFSET(CPU_FP_REGS)
-       bl      __fpsimd_restore_state
-
-       // Skip restoring fpexc32 for AArch64 guests
-       mrs     x1, hcr_el2
-       tbnz    x1, #HCR_RW_SHIFT, 1f
-       ldr     x4, [x3, #VCPU_FPEXC32_EL2]
-       msr     fpexc32_el2, x4
-1:
-       ldp     x4, lr, [sp], #16
-       ldp     x2, x3, [sp], #16
-       ldp     x0, x1, [sp], #16
-
+       stp     x2, x3, [sp, #-144]!
+       stp     x4, x5, [sp, #16]
+       stp     x6, x7, [sp, #32]
+       stp     x8, x9, [sp, #48]
+       stp     x10, x11, [sp, #64]
+       stp     x12, x13, [sp, #80]
+       stp     x14, x15, [sp, #96]
+       stp     x16, x17, [sp, #112]
+       stp     x18, lr, [sp, #128]
+
+       bl      __hyp_switch_fpsimd
+
+       ldp     x4, x5, [sp, #16]
+       ldp     x6, x7, [sp, #32]
+       ldp     x8, x9, [sp, #48]
+       ldp     x10, x11, [sp, #64]
+       ldp     x12, x13, [sp, #80]
+       ldp     x14, x15, [sp, #96]
+       ldp     x16, x17, [sp, #112]
+       ldp     x18, lr, [sp, #128]
+       ldp     x0, x1, [sp, #144]
+       ldp     x2, x3, [sp], #160
        eret
 ENDPROC(__fpsimd_guest_restore)

diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c
index d9645236e474972ee92c5482bcd0348773ceaf07..c0796c4d93a53bf49927930706c980fb8f933f07 100644 (file)
--- a/arch/arm64/kvm/hyp/switch.c
+++ b/arch/arm64/kvm/hyp/switch.c
@@ -318,6 +318,30 @@ static bool __hyp_text __skip_instr(struct kvm_vcpu *vcpu)
        }
 }
 
+void __hyp_text __hyp_switch_fpsimd(u64 esr __always_unused,
+                                   struct kvm_vcpu *vcpu)
+{
+       kvm_cpu_context_t *host_ctxt;
+
+       if (has_vhe())
+               write_sysreg(read_sysreg(cpacr_el1) | CPACR_EL1_FPEN,
+                            cpacr_el1);
+       else
+               write_sysreg(read_sysreg(cptr_el2) & ~(u64)CPTR_EL2_TFP,
+                            cptr_el2);
+
+       isb();
+
+       host_ctxt = kern_hyp_va(vcpu->arch.host_cpu_context);
+       __fpsimd_save_state(&host_ctxt->gp_regs.fp_regs);
+       __fpsimd_restore_state(&vcpu->arch.ctxt.gp_regs.fp_regs);
+
+       /* Skip restoring fpexc32 for AArch64 guests */
+       if (!(read_sysreg(hcr_el2) & HCR_RW))
+               write_sysreg(vcpu->arch.ctxt.sys_regs[FPEXC32_EL2],
+                            fpexc32_el2);
+}
+
 /*
  * Return true when we were able to fixup the guest exit and should return to
  * the guest, false when we should restore the host state and return to the