Patchwork [2/2,v3] KVM: PPC: Added one_reg interface for timer registers

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Submitter Bharat Bhushan
Date Feb. 25, 2013, 4:57 a.m.
Message ID <1361768232-5529-3-git-send-email-bharat.bhushan@freescale.com>
Download mbox | patch
Permalink /patch/222846/
State New
Headers show

Comments

Bharat Bhushan - Feb. 25, 2013, 4:57 a.m.
If userspace wants to change some specific bits of TSR
(timer status register) then it uses GET/SET_SREGS ioctl interface.
So the steps will be:
      i)   user-space will make get ioctl,
      ii)  change TSR in userspace
      iii) then make set ioctl.
It can happen that TSR gets changed by kernel after step i) and
before step iii).

To avoid this we have added below one_reg ioctls for oring and clearing
specific bits in TSR. This patch adds one registerface for:
     1) setting specific bit in TSR (timer status register)
     2) clearing specific bit in TSR (timer status register)
     3) setting/getting the TCR register. There are cases where we want to only
        change TCR and not TSR. Although we can uses SREGS without
        KVM_SREGS_E_UPDATE_TSR flag but I think one reg is better. I am open
        if someone feels we should use SREGS only here.
     4) getting/setting TSR register

Signed-off-by: Bharat Bhushan <bharat.bhushan@freescale.com>
---
v3: No change
v2: Added Documentation

 Documentation/virtual/kvm/api.txt   |    4 ++++
 arch/powerpc/include/uapi/asm/kvm.h |    5 +++++
 arch/powerpc/kvm/booke.c            |   30 ++++++++++++++++++++++++++++++
 3 files changed, 39 insertions(+), 0 deletions(-)

Patch

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index c2534c3..cce500a 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -1762,6 +1762,10 @@  registers, find a list below:
   PPC   | KVM_REG_PPC_VPA_DTL   | 128
   PPC   | KVM_REG_PPC_EPCR	| 32
   PPC   | KVM_REG_PPC_EPR	| 32
+  PPC   | KVM_REG_PPC_TCR	| 32
+  PPC   | KVM_REG_PPC_TSR	| 32
+  PPC   | KVM_REG_PPC_OR_TSR	| 32
+  PPC   | KVM_REG_PPC_CLEAR_TSR	| 32
 
 4.69 KVM_GET_ONE_REG
 
diff --git a/arch/powerpc/include/uapi/asm/kvm.h b/arch/powerpc/include/uapi/asm/kvm.h
index 16064d0..ef072b1 100644
--- a/arch/powerpc/include/uapi/asm/kvm.h
+++ b/arch/powerpc/include/uapi/asm/kvm.h
@@ -417,4 +417,9 @@  struct kvm_get_htab_header {
 #define KVM_REG_PPC_EPCR	(KVM_REG_PPC | KVM_REG_SIZE_U32 | 0x85)
 #define KVM_REG_PPC_EPR		(KVM_REG_PPC | KVM_REG_SIZE_U32 | 0x86)
 
+/* Timer Status Register OR/CLEAR interface */
+#define KVM_REG_PPC_OR_TSR	(KVM_REG_PPC | KVM_REG_SIZE_U32 | 0x87)
+#define KVM_REG_PPC_CLEAR_TSR	(KVM_REG_PPC | KVM_REG_SIZE_U32 | 0x88)
+#define KVM_REG_PPC_TCR		(KVM_REG_PPC | KVM_REG_SIZE_U32 | 0x89)
+#define KVM_REG_PPC_TSR		(KVM_REG_PPC | KVM_REG_SIZE_U32 | 0x8a)
 #endif /* __LINUX_KVM_POWERPC_H */
diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index 03f7bb3..8b553c0 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -1442,6 +1442,12 @@  int kvm_vcpu_ioctl_get_one_reg(struct kvm_vcpu *vcpu, struct kvm_one_reg *reg)
 		r = put_user(vcpu->arch.epcr, (u32 __user *)(long)reg->addr);
 		break;
 #endif
+	case KVM_REG_PPC_TCR:
+		r = put_user(vcpu->arch.tcr, (u32 __user *)(long)reg->addr);
+		break;
+	case KVM_REG_PPC_TSR:
+		r = put_user(vcpu->arch.tsr, (u32 __user *)(long)reg->addr);
+		break;
 	default:
 		break;
 	}
@@ -1485,6 +1491,30 @@  int kvm_vcpu_ioctl_set_one_reg(struct kvm_vcpu *vcpu, struct kvm_one_reg *reg)
 		break;
 	}
 #endif
+	case KVM_REG_PPC_OR_TSR: {
+		u32 tsr_bits;
+		r = get_user(tsr_bits, (u32 __user *)(long)reg->addr);
+		kvmppc_set_tsr_bits(vcpu, tsr_bits);
+		break;
+	}
+	case KVM_REG_PPC_CLEAR_TSR: {
+		u32 tsr_bits;
+		r = get_user(tsr_bits, (u32 __user *)(long)reg->addr);
+		kvmppc_clr_tsr_bits(vcpu, tsr_bits);
+		break;
+	}
+	case KVM_REG_PPC_TSR: {
+		u32 tsr;
+		r = get_user(tsr, (u32 __user *)(long)reg->addr);
+		kvmppc_set_tsr(vcpu, tsr);
+		break;
+	}
+	case KVM_REG_PPC_TCR: {
+		u32 tcr;
+		r = get_user(tcr, (u32 __user *)(long)reg->addr);
+		kvmppc_set_tcr(vcpu, tcr);
+		break;
+	}
 	default:
 		break;
 	}