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[09/14] MIPS: KVM: Omit FPU handling entry code if possible

Message ID 1466699687-24791-10-git-send-email-james.hogan@imgtec.com (mailing list archive)
State New, archived
Headers show

Commit Message

James Hogan June 23, 2016, 4:34 p.m. UTC 
The FPU handling code on entry from guest is unnecessary if no FPU is
present, so allow it to be dropped at uasm assembly time.

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
---
 arch/mips/kvm/entry.c | 27 +++++++++++++++------------
 1 file changed, 15 insertions(+), 12 deletions(-)
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Patch

diff --git a/arch/mips/kvm/entry.c b/arch/mips/kvm/entry.c
index 9a18b4939b35..c0d9f551c1c1 100644
--- a/arch/mips/kvm/entry.c
+++ b/arch/mips/kvm/entry.c
@@ -393,18 +393,21 @@  void *kvm_mips_build_exit(void *addr)
 	UASM_i_LW(&p, K0, uasm_rel_lo((long)&ebase), K0);
 	uasm_i_mtc0(&p, K0, C0_EBASE);
 
-	/*
-	 * If FPU is enabled, save FCR31 and clear it so that later ctc1's don't
-	 * trigger FPE for pending exceptions.
-	 */
-	uasm_i_lui(&p, AT, ST0_CU1 >> 16);
-	uasm_i_and(&p, V1, V0, AT);
-	uasm_il_beqz(&p, &r, V1, label_fpu_1);
-	 uasm_i_nop(&p);
-	uasm_i_cfc1(&p, T0, 31);
-	uasm_i_sw(&p, T0, offsetof(struct kvm_vcpu_arch, fpu.fcr31), K1);
-	uasm_i_ctc1(&p, ZERO, 31);
-	uasm_l_fpu_1(&l, p);
+	if (raw_cpu_has_fpu) {
+		/*
+		 * If FPU is enabled, save FCR31 and clear it so that later
+		 * ctc1's don't trigger FPE for pending exceptions.
+		 */
+		uasm_i_lui(&p, AT, ST0_CU1 >> 16);
+		uasm_i_and(&p, V1, V0, AT);
+		uasm_il_beqz(&p, &r, V1, label_fpu_1);
+		 uasm_i_nop(&p);
+		uasm_i_cfc1(&p, T0, 31);
+		uasm_i_sw(&p, T0, offsetof(struct kvm_vcpu_arch, fpu.fcr31),
+			  K1);
+		uasm_i_ctc1(&p, ZERO, 31);
+		uasm_l_fpu_1(&l, p);
+	}
 
 #ifdef CONFIG_CPU_HAS_MSA
 	/*