From d37f4038d16273087bdc60387807b90a8c06da7f Mon Sep 17 00:00:00 2001 From: James Hogan Date: Thu, 23 Jun 2016 17:34:42 +0100 Subject: [PATCH] MIPS: KVM: Omit FPU handling entry code if possible MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Cc: Paolo Bonzini Cc: Radim KrÄmář Cc: Ralf Baechle Cc: linux-mips@linux-mips.org Cc: kvm@vger.kernel.org Signed-off-by: Paolo Bonzini --- arch/mips/kvm/entry.c | 27 +++++++++++++++------------ 1 file changed, 15 insertions(+), 12 deletions(-) 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 /*