From 9a7a9b09fee8487003df012d9af4b227b3661e4d Mon Sep 17 00:00:00 2001 From: Alexander Graf Date: Fri, 30 Oct 2009 05:47:15 +0000 Subject: [PATCH] Add mfdec emulation We support setting the DEC to a certain value right now. Doing that basically triggers the CPU local timer. But there's also an mfdec command that enabled the OS to read the decrementor. This is required at least by all desktop and server PowerPC Linux kernels. It can't really hurt to allow embedded ones to do it as well though. Signed-off-by: Alexander Graf Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/kvm/emulate.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/kvm/emulate.c b/arch/powerpc/kvm/emulate.c index 7737146af3fb..50d411d946eb 100644 --- a/arch/powerpc/kvm/emulate.c +++ b/arch/powerpc/kvm/emulate.c @@ -66,12 +66,14 @@ void kvmppc_emulate_dec(struct kvm_vcpu *vcpu) { + unsigned long nr_jiffies; + if (vcpu->arch.tcr & TCR_DIE) { /* The decrementer ticks at the same rate as the timebase, so * that's how we convert the guest DEC value to the number of * host ticks. */ - unsigned long nr_jiffies; + vcpu->arch.dec_jiffies = mftb(); nr_jiffies = vcpu->arch.dec / tb_ticks_per_jiffy; mod_timer(&vcpu->arch.dec_timer, get_jiffies_64() + nr_jiffies); @@ -211,6 +213,15 @@ int kvmppc_emulate_instruction(struct kvm_run *run, struct kvm_vcpu *vcpu) /* Note: SPRG4-7 are user-readable, so we don't get * a trap. */ + case SPRN_DEC: + { + u64 jd = mftb() - vcpu->arch.dec_jiffies; + vcpu->arch.gpr[rt] = vcpu->arch.dec - jd; +#ifdef DEBUG_EMUL + printk(KERN_INFO "mfDEC: %x - %llx = %lx\n", vcpu->arch.dec, jd, vcpu->arch.gpr[rt]); +#endif + break; + } default: emulated = kvmppc_core_emulate_mfspr(vcpu, sprn, rt); if (emulated == EMULATE_FAIL) {