On 05/16/2012 11:21 AM, Bhushan Bharat-R65777 wrote:
-----Original Message-----
From: Alexander Graf [mailto:agraf@xxxxxxx]
Sent: Wednesday, May 16, 2012 2:36 PM
To: Bhushan Bharat-R65777
Cc: kvm-ppc@xxxxxxxxxxxxxxx
Subject: Re: [PATCH] KVM: PPC: booke: Added DECAR support
On 05/16/2012 08:57 AM, Bhushan Bharat-R65777 wrote:
-----Original Message-----
From: Alexander Graf [mailto:agraf@xxxxxxx]
Sent: Tuesday, May 15, 2012 7:59 PM
To: Bhushan Bharat-R65777
Cc: kvm-ppc@xxxxxxxxxxxxxxx; Bhushan Bharat-R65777
Subject: Re: [PATCH] KVM: PPC: booke: Added DECAR support
On 05/15/2012 09:33 AM, Bharat Bhushan wrote:
Added the decrementer auto-reload support.
Signed-off-by: Bharat Bhushan<bharat.bhushan@xxxxxxxxxxxxx>
---
arch/powerpc/include/asm/kvm_host.h | 2 ++
arch/powerpc/kvm/booke.c | 5 +++++
arch/powerpc/kvm/booke_emulate.c | 7 ++++++-
3 files changed, 13 insertions(+), 1 deletions(-)
diff --git a/arch/powerpc/include/asm/kvm_host.h
b/arch/powerpc/include/asm/kvm_host.h
index d848cdc..1d6f89e 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -414,7 +414,9 @@ struct kvm_vcpu_arch {
ulong mcsrr1;
ulong mcsr;
u32 dec;
+#ifdef CONFIG_BOOKE
u32 decar;
+#endif
u32 tbl;
u32 tbu;
u32 tcr;
diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index 72f13f4..86681ee 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -1267,6 +1267,11 @@ void kvmppc_decrementer_func(unsigned long data)
{
struct kvm_vcpu *vcpu = (struct kvm_vcpu *)data;
+ if (vcpu->arch.tcr& TCR_ARE) {
+ vcpu->arch.dec = vcpu->arch.decar;
+ kvmppc_emulate_dec(vcpu);
+ }
+
kvmppc_set_tsr_bits(vcpu, TSR_DIS);
}
diff --git a/arch/powerpc/kvm/booke_emulate.c
b/arch/powerpc/kvm/booke_emulate.c
index 6c76397..83c3796 100644
--- a/arch/powerpc/kvm/booke_emulate.c
+++ b/arch/powerpc/kvm/booke_emulate.c
@@ -129,6 +129,9 @@ int kvmppc_booke_emulate_mtspr(struct kvm_vcpu
*vcpu, int
sprn, ulong spr_val)
kvmppc_set_tcr(vcpu, spr_val);
break;
+ case SPRN_DECAR:
+ vcpu->arch.decar = spr_val;
+ break;
/*
* Note: SPRG4-7 are user-readable.
* These values are loaded into the real SPRGs when resuming the
@@
-244,7 +247,9 @@ int kvmppc_booke_emulate_mfspr(struct kvm_vcpu
*vcpu, int
sprn, ulong *spr_val)
case SPRN_TCR:
*spr_val = vcpu->arch.tcr;
break;
-
+ case SPRN_DECAR:
+ *spr_val = vcpu->arch.decar;
+ break;
DECAR can't be read. Otherwise looks good to me.
DECAR can be read on e500mc cores. So I will make this under
CONFIG_KVM_E500MC.
What happens if DECAR is read on non e500mc? Is it treated as NOP or illegal
instruction exception?
I would assume the latter. NOPs usually don't happen. If anything, it would
return 0.
See section 9.4 in the PowerISA:
The contents of the Decrementer Auto-Reload Register cannot be read. The
contents of bits 32:63 of register RS can be written to the Decrementer Auto-
Reload Register using the mtspr instruction.
Could you please paste the respective passage of the e500mc manual that declares
DECAR as readable?
I have booke -4 version 1.05.
There are remarks at 3 place
1)
Table 2-1:
There is remark " DECAR is defined by the architecture to be write-only, however the e500mc allows it to be read."
------------
2)
2.8.5 Decrementer Auto-Reload Register (DECAR)
"For e500V4, the DECAR can be read in hypervisor state, although the architecture defines it as a
write-only register."
--------------
3)
Table 4.37
Hypervisor Privilege on Read - Yes
Hypervisor Privilege on Write - Yes
Remark: e500mc allows reading of DECAR although Power ISA does not define it.
----------------
I verified with my unit test that reading DECAR traps in KVM on e500mc.
Alrighty, so how about putting the read into e500_emulate.c then? What
does e500v2 do here?
Alex
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