KVM: PPC: Book3S HV: Support POWER6 compatibility mode on POWER7

This enables us to use the Processor Compatibility Register (PCR) on
POWER7 to put the processor into architecture 2.05 compatibility mode
when running a guest.  In this mode the new instructions and registers
that were introduced on POWER7 are disabled in user mode.  This
includes all the VSX facilities plus several other instructions such
as ldbrx, stdbrx, popcntw, popcntd, etc.

To select this mode, we have a new register accessible through the
set/get_one_reg interface, called KVM_REG_PPC_ARCH_COMPAT.  Setting
this to zero gives the full set of capabilities of the processor.
Setting it to one of the "logical" PVR values defined in PAPR puts
the vcpu into the compatibility mode for the corresponding
architecture level.  The supported values are:

0x0f000002	Architecture 2.05 (POWER6)
0x0f000003	Architecture 2.06 (POWER7)
0x0f100003	Architecture 2.06+ (POWER7+)

Since the PCR is per-core, the architecture compatibility level and
the corresponding PCR value are stored in the struct kvmppc_vcore, and
are therefore shared between all vcpus in a virtual core.

Signed-off-by: Paul Mackerras <paulus@samba.org>
[agraf: squash in fix to add missing break statements and documentation]
Signed-off-by: Alexander Graf <agraf@suse.de>

6 files changed, 66 insertions, 2 deletions

diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 4934e13fb23c..b1e8f2ba2a9d 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -291,6 +291,8 @@ struct kvmppc_vcore {
         struct kvm_vcpu *runner;
         u64 tb_offset;          /* guest timebase - host timebase */
         ulong lpcr;
+        u32 arch_compat;
+        ulong pcr;
 };
 
 #define VCORE_ENTRY_COUNT(vc)   ((vc)->entry_exit_count & 0xff)
diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index 4bec4df3fb98..e294673e9d4b 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -314,6 +314,10 @@
 #define   LPID_RSVD     0x3ff           /* Reserved LPID for partn switching */
 #define SPRN_HMER       0x150   /* Hardware m? error recovery */
 #define SPRN_HMEER      0x151   /* Hardware m? enable error recovery */
+#define SPRN_PCR        0x152   /* Processor compatibility register */
+#define   PCR_VEC_DIS   (1ul << (63-0)) /* Vec. disable (bit NA since POWER8) */
+#define   PCR_VSX_DIS   (1ul << (63-1)) /* VSX disable (bit NA since POWER8) */
+#define   PCR_ARCH_205  0x2             /* Architecture 2.05 */
 #define SPRN_HEIR       0x153   /* Hypervisor Emulated Instruction Register */
 #define SPRN_TLBINDEXR  0x154   /* P7 TLB control register */
 #define SPRN_TLBVPNR    0x155   /* P7 TLB control register */
@@ -1106,6 +1110,13 @@
 #define PVR_BE          0x0070
 #define PVR_PA6T        0x0090
 
+/* "Logical" PVR values defined in PAPR, representing architecture levels */
+#define PVR_ARCH_204    0x0f000001
+#define PVR_ARCH_205    0x0f000002
+#define PVR_ARCH_206    0x0f000003
+#define PVR_ARCH_206p   0x0f100003
+#define PVR_ARCH_207    0x0f000004
+
 /* Macros for setting and retrieving special purpose registers */
 #ifndef __ASSEMBLY__
 #define mfmsr()         ({unsigned long rval; \
diff --git a/arch/powerpc/include/uapi/asm/kvm.h b/arch/powerpc/include/uapi/asm/kvm.h
index fab6bc1f8e90..e420d46d363f 100644
--- a/arch/powerpc/include/uapi/asm/kvm.h
+++ b/arch/powerpc/include/uapi/asm/kvm.h
@@ -536,6 +536,9 @@ struct kvm_get_htab_header {
 #define KVM_REG_PPC_LPCR        (KVM_REG_PPC | KVM_REG_SIZE_U32 | 0xb5)
 #define KVM_REG_PPC_PPR         (KVM_REG_PPC | KVM_REG_SIZE_U64 | 0xb6)
 
+/* Architecture compatibility level */
+#define KVM_REG_PPC_ARCH_COMPAT (KVM_REG_PPC | KVM_REG_SIZE_U32 | 0xb7)
+
 /* Transactional Memory checkpointed state:
  * This is all GPRs, all VSX regs and a subset of SPRs
  */
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index 5fda4ef489ad..5a285efba174 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -526,6 +526,7 @@ int main(void)
         DEFINE(VCORE_NAPPING_THREADS, offsetof(struct kvmppc_vcore, napping_threads));
         DEFINE(VCORE_TB_OFFSET, offsetof(struct kvmppc_vcore, tb_offset));
         DEFINE(VCORE_LPCR, offsetof(struct kvmppc_vcore, lpcr));
+        DEFINE(VCORE_PCR, offsetof(struct kvmppc_vcore, pcr));
         DEFINE(VCPU_SVCPU, offsetof(struct kvmppc_vcpu_book3s, shadow_vcpu) -
                            offsetof(struct kvmppc_vcpu_book3s, vcpu));
         DEFINE(VCPU_SLB_E, offsetof(struct kvmppc_slb, orige));
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 2a0e38feec1d..e42fb5448608 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -166,6 +166,35 @@ void kvmppc_set_pvr(struct kvm_vcpu *vcpu, u32 pvr)
         vcpu->arch.pvr = pvr;
 }
 
+int kvmppc_set_arch_compat(struct kvm_vcpu *vcpu, u32 arch_compat)
+{
+        unsigned long pcr = 0;
+        struct kvmppc_vcore *vc = vcpu->arch.vcore;
+
+        if (arch_compat) {
+                if (!cpu_has_feature(CPU_FTR_ARCH_206))
+                        return -EINVAL; /* 970 has no compat mode support */
+
+                switch (arch_compat) {
+                case PVR_ARCH_205:
+                        pcr = PCR_ARCH_205;
+                        break;
+                case PVR_ARCH_206:
+                case PVR_ARCH_206p:
+                        break;
+                default:
+                        return -EINVAL;
+                }
+        }
+
+        spin_lock(&vc->lock);
+        vc->arch_compat = arch_compat;
+        vc->pcr = pcr;
+        spin_unlock(&vc->lock);
+
+        return 0;
+}
+
 void kvmppc_dump_regs(struct kvm_vcpu *vcpu)
 {
         int r;
@@ -826,6 +855,9 @@ int kvmppc_get_one_reg(struct kvm_vcpu *vcpu, u64 id, union kvmppc_one_reg *val)
         case KVM_REG_PPC_PPR:
                 *val = get_reg_val(id, vcpu->arch.ppr);
                 break;
+        case KVM_REG_PPC_ARCH_COMPAT:
+                *val = get_reg_val(id, vcpu->arch.vcore->arch_compat);
+                break;
         default:
                 r = -EINVAL;
                 break;
@@ -936,6 +968,9 @@ int kvmppc_set_one_reg(struct kvm_vcpu *vcpu, u64 id, union kvmppc_one_reg *val)
         case KVM_REG_PPC_PPR:
                 vcpu->arch.ppr = set_reg_val(id, *val);
                 break;
+        case KVM_REG_PPC_ARCH_COMPAT:
+                r = kvmppc_set_arch_compat(vcpu, set_reg_val(id, *val));
+                break;
         default:
                 r = -EINVAL;
                 break;
diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index a81979becf41..cd39632a646e 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -499,7 +499,13 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_201)
         addis   r8,r8,0x100     /* if so, increment upper 40 bits */
         mtspr   SPRN_TBU40,r8
 
-37:     li      r0,1
+        /* Load guest PCR value to select appropriate compat mode */
+37:     ld      r7, VCORE_PCR(r5)
+        cmpdi   r7, 0
+        beq     38f
+        mtspr   SPRN_PCR, r7
+38:
+        li      r0,1
         stb     r0,VCORE_IN_GUEST(r5)   /* signal secondaries to continue */
         b       10f
 
@@ -1094,8 +1100,14 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_201)
         addis   r8,r8,0x100             /* if so, increment upper 40 bits */
         mtspr   SPRN_TBU40,r8
 
+        /* Reset PCR */
+17:     ld      r0, VCORE_PCR(r5)
+        cmpdi   r0, 0
+        beq     18f
+        li      r0, 0
+        mtspr   SPRN_PCR, r0
+18:
         /* Signal secondary CPUs to continue */
-17:     li      r0,0
         stb     r0,VCORE_IN_GUEST(r5)
         lis     r8,0x7fff               /* MAX_INT@h */
         mtspr   SPRN_HDEC,r8