Currently the reserved bits of the Processor Compatibility Register
(PCR) are cleared as per the Programming Note in Section 1.3.3 of
version 3.0B of the Power ISA. This causes all new architecture
features to be made available when running on newer processors with
new architecture features added to the PCR as bits must be set to
disable a given feature.
For example to disable new features added as part of Version 2.07 of
the ISA the corresponding bit in the PCR needs to be set.
As new processor features generally require explicit kernel support
they should be disabled until such support is implemented. Therefore
kernels should set all unknown/reserved bits in the PCR such that any
new architecture features which the kernel does not currently know
about get disabled.
An update is planned to the ISA to clarify that the PCR is an
exception to the Programming Note on reserved bits in Section 1.3.3.
Signed-off-by: Alistair Popple <alist...@popple.id.au>
Signed-off-by: Jordan Niethe <jniet...@gmail.com>
Tested-by: Joel Stanley <j...@jms.id.au>
---
v2: Added some clarifications to the commit message
---
arch/powerpc/include/asm/reg.h | 3 +++
arch/powerpc/kernel/cpu_setup_power.S | 6 ++++++
arch/powerpc/kernel/dt_cpu_ftrs.c | 3 ++-
arch/powerpc/kvm/book3s_hv.c | 11 +++++++----
arch/powerpc/kvm/book3s_hv_nested.c | 6 +++---
arch/powerpc/kvm/book3s_hv_rmhandlers.S | 10 ++++++----
6 files changed, 27 insertions(+), 12 deletions(-)
diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index 10caa145f98b..258435c75c43 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -475,6 +475,7 @@
#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_TM_DIS (1ul << (63-2)) /* Trans. memory disable (POWER8) */
+#define PCR_HIGH_BITS (PCR_VEC_DIS | PCR_VSX_DIS | PCR_TM_DIS)
/*
* These bits are used in the function kvmppc_set_arch_compat() to specify and
* determine both the compatibility level which we want to emulate and the
@@ -483,6 +484,8 @@
#define PCR_ARCH_207 0x8 /* Architecture 2.07 */
#define PCR_ARCH_206 0x4 /* Architecture 2.06 */
#define PCR_ARCH_205 0x2 /* Architecture 2.05 */
+#define PCR_LOW_BITS (PCR_ARCH_207 | PCR_ARCH_206 | PCR_ARCH_205)
+#define PCR_MASK ~(PCR_HIGH_BITS | PCR_LOW_BITS) /* PCR Reserved Bits */
#define SPRN_HEIR 0x153 /* Hypervisor Emulated Instruction
Register */
#define SPRN_TLBINDEXR 0x154 /* P7 TLB control register */
#define SPRN_TLBVPNR 0x155 /* P7 TLB control register */
diff --git a/arch/powerpc/kernel/cpu_setup_power.S
b/arch/powerpc/kernel/cpu_setup_power.S
index 3239a9fe6c1c..a460298c7ddb 100644
--- a/arch/powerpc/kernel/cpu_setup_power.S
+++ b/arch/powerpc/kernel/cpu_setup_power.S
@@ -23,6 +23,7 @@ _GLOBAL(__setup_cpu_power7)
beqlr
li r0,0
mtspr SPRN_LPID,r0
+ LOAD_REG_IMMEDIATE(r0, PCR_MASK)
mtspr SPRN_PCR,r0
mfspr r3,SPRN_LPCR
li r4,(LPCR_LPES1 >> LPCR_LPES_SH)
@@ -37,6 +38,7 @@ _GLOBAL(__restore_cpu_power7)
beqlr
li r0,0
mtspr SPRN_LPID,r0
+ LOAD_REG_IMMEDIATE(r0, PCR_MASK)
mtspr SPRN_PCR,r0
mfspr r3,SPRN_LPCR
li r4,(LPCR_LPES1 >> LPCR_LPES_SH)
@@ -54,6 +56,7 @@ _GLOBAL(__setup_cpu_power8)
beqlr
li r0,0
mtspr SPRN_LPID,r0
+ LOAD_REG_IMMEDIATE(r0, PCR_MASK)
mtspr SPRN_PCR,r0
mfspr r3,SPRN_LPCR
ori r3, r3, LPCR_PECEDH
@@ -76,6 +79,7 @@ _GLOBAL(__restore_cpu_power8)
beqlr
li r0,0
mtspr SPRN_LPID,r0
+ LOAD_REG_IMMEDIATE(r0, PCR_MASK)
mtspr SPRN_PCR,r0
mfspr r3,SPRN_LPCR
ori r3, r3, LPCR_PECEDH
@@ -98,6 +102,7 @@ _GLOBAL(__setup_cpu_power9)
mtspr SPRN_PSSCR,r0
mtspr SPRN_LPID,r0
mtspr SPRN_PID,r0
+ LOAD_REG_IMMEDIATE(r0, PCR_MASK)
mtspr SPRN_PCR,r0
mfspr r3,SPRN_LPCR
LOAD_REG_IMMEDIATE(r4, LPCR_PECEDH | LPCR_PECE_HVEE | LPCR_HVICE |
LPCR_HEIC)
@@ -123,6 +128,7 @@ _GLOBAL(__restore_cpu_power9)
mtspr SPRN_PSSCR,r0
mtspr SPRN_LPID,r0
mtspr SPRN_PID,r0
+ LOAD_REG_IMMEDIATE(r0, PCR_MASK)
mtspr SPRN_PCR,r0
mfspr r3,SPRN_LPCR
LOAD_REG_IMMEDIATE(r4, LPCR_PECEDH | LPCR_PECE_HVEE | LPCR_HVICE |
LPCR_HEIC)
diff --git a/arch/powerpc/kernel/dt_cpu_ftrs.c
b/arch/powerpc/kernel/dt_cpu_ftrs.c
index bd95318d2202..bceee2fde885 100644
--- a/arch/powerpc/kernel/dt_cpu_ftrs.c
+++ b/arch/powerpc/kernel/dt_cpu_ftrs.c
@@ -101,7 +101,7 @@ static void __restore_cpu_cpufeatures(void)
if (hv_mode) {
mtspr(SPRN_LPID, 0);
mtspr(SPRN_HFSCR, system_registers.hfscr);
- mtspr(SPRN_PCR, 0);
+ mtspr(SPRN_PCR, PCR_MASK);
}
mtspr(SPRN_FSCR, system_registers.fscr);
@@ -144,6 +144,7 @@ static void __init cpufeatures_setup_cpu(void)
mtspr(SPRN_HFSCR, 0);
}
mtspr(SPRN_FSCR, 0);
+ mtspr(SPRN_PCR, PCR_MASK);
/*
* LPCR does not get cleared, to match behaviour with secondaries
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index cde3f5a4b3e4..7a133c3aebe6 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -401,8 +401,11 @@ static int kvmppc_set_arch_compat(struct kvm_vcpu *vcpu,
u32 arch_compat)
spin_lock(&vc->lock);
vc->arch_compat = arch_compat;
- /* Set all PCR bits for which guest_pcr_bit <= bit < host_pcr_bit */
- vc->pcr = host_pcr_bit - guest_pcr_bit;
+ /*
+ * Set all PCR bits for which guest_pcr_bit <= bit < host_pcr_bit
+ * Also set all reserved PCR bits
+ */
+ vc->pcr = (host_pcr_bit - guest_pcr_bit) | PCR_MASK;
spin_unlock(&vc->lock);
return 0;
@@ -3398,7 +3401,7 @@ static int kvmhv_load_hv_regs_and_go(struct kvm_vcpu
*vcpu, u64 time_limit,
}
if (vc->pcr)
- mtspr(SPRN_PCR, vc->pcr);
+ mtspr(SPRN_PCR, vc->pcr | PCR_MASK);
mtspr(SPRN_DPDES, vc->dpdes);
mtspr(SPRN_VTB, vc->vtb);
@@ -3478,7 +3481,7 @@ static int kvmhv_load_hv_regs_and_go(struct kvm_vcpu
*vcpu, u64 time_limit,
vc->vtb = mfspr(SPRN_VTB);
mtspr(SPRN_DPDES, 0);
if (vc->pcr)
- mtspr(SPRN_PCR, 0);
+ mtspr(SPRN_PCR, PCR_MASK);
if (vc->tb_offset_applied) {
u64 new_tb = mftb() - vc->tb_offset_applied;
diff --git a/arch/powerpc/kvm/book3s_hv_nested.c
b/arch/powerpc/kvm/book3s_hv_nested.c
index 735e0ac6f5b2..e916522c5c39 100644
--- a/arch/powerpc/kvm/book3s_hv_nested.c
+++ b/arch/powerpc/kvm/book3s_hv_nested.c
@@ -29,7 +29,7 @@ void kvmhv_save_hv_regs(struct kvm_vcpu *vcpu, struct
hv_guest_state *hr)
{
struct kvmppc_vcore *vc = vcpu->arch.vcore;
- hr->pcr = vc->pcr;
+ hr->pcr = vc->pcr | PCR_MASK;
hr->dpdes = vc->dpdes;
hr->hfscr = vcpu->arch.hfscr;
hr->tb_offset = vc->tb_offset;
@@ -65,7 +65,7 @@ static void byteswap_hv_regs(struct hv_guest_state *hr)
hr->lpid = swab32(hr->lpid);
hr->vcpu_token = swab32(hr->vcpu_token);
hr->lpcr = swab64(hr->lpcr);
- hr->pcr = swab64(hr->pcr);
+ hr->pcr = swab64(hr->pcr) | PCR_MASK;
hr->amor = swab64(hr->amor);
hr->dpdes = swab64(hr->dpdes);
hr->hfscr = swab64(hr->hfscr);
@@ -148,7 +148,7 @@ static void restore_hv_regs(struct kvm_vcpu *vcpu, struct
hv_guest_state *hr)
{
struct kvmppc_vcore *vc = vcpu->arch.vcore;
- vc->pcr = hr->pcr;
+ vc->pcr = hr->pcr | PCR_MASK;
vc->dpdes = hr->dpdes;
vcpu->arch.hfscr = hr->hfscr;
vcpu->arch.dawr = hr->dawr0;
diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index 337e64468d78..f21dee7a1757 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -643,8 +643,10 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300)
/* Load guest PCR value to select appropriate compat mode */
37: ld r7, VCORE_PCR(r5)
- cmpdi r7, 0
+ LOAD_REG_IMMEDIATE(r6, PCR_MASK)
+ cmpld r7, r6
beq 38f
+ or r7, r7, r6
mtspr SPRN_PCR, r7
38:
@@ -1884,10 +1886,10 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
/* Reset PCR */
ld r0, VCORE_PCR(r5)
- cmpdi r0, 0
+ LOAD_REG_IMMEDIATE(r6, PCR_MASK)
+ cmpld r0, r6
beq 18f
- li r0, 0
- mtspr SPRN_PCR, r0
+ mtspr SPRN_PCR, r6
18:
/* Signal secondary CPUs to continue */
stb r0,VCORE_IN_GUEST(r5)
--
2.20.1
