powerpc/64s: Fix Power9 DD2.0 workarounds by adding DD2.1 feature

Recently we added a CPU feature for Power9 DD2.0, to capture the fact
that some workarounds are required only on Power9 DD1 and DD2.0 but
not DD2.1 or later.

Then in commit 1590fd452faa ("powerpc/64s/idle: avoid POWER9 DD1 and
DD2.0 ERAT workaround on DD2.1") and commit 64e2eab9f9c4
"powerpc/64s/idle: avoid POWER9 DD1 and DD2.0 PMU workaround on
DD2.1") we changed CPU_FTR_SECTIONs to check for DD1 or DD20, eg:

  BEGIN_FTR_SECTION
          PPC_INVALIDATE_ERAT
  END_FTR_SECTION_IFSET(CPU_FTR_POWER9_DD1 | CPU_FTR_POWER9_DD20)

Unfortunately although this reads as "if set DD1 or DD2.0", the or is
a bitwise or and actually generates a mask of both bits. The code that
does the feature patching then checks that the value of the CPU
features masked with that mask are equal to the mask.

So the end result is we're checking for DD1 and DD20 being set, which
never happens. Yes the API is terrible.

Removing the ERAT workaround on DD2.0 results in random SEGVs, the
system tends to boot, but things randomly die including sometimes
dhclient, udev etc.

To fix the problem and hopefully avoid it in future, we remove the
DD2.0 CPU feature and instead add a DD2.1 (or later) feature. This
allows us to easily express that the workarounds are required if DD2.1
is not set.

At some point we will drop the DD1 workarounds entirely and some of
this can be cleaned up.

Fixes: 1590fd452faa ("powerpc/64s/idle: avoid POWER9 DD1 and DD2.0 ERAT workaround on DD2.1")
Fixes: 64e2eab9f9c4 ("powerpc/64s/idle: avoid POWER9 DD1 and DD2.0 PMU workaround on DD2.1")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/include/asm/cputable.h b/arch/powerpc/include/asm/cputable.h
index 1ca26ca85ec669f2bcfead1d087c5060398493f0..04c31db5e7c3cea4ab8650d57e4bb87c49a649f0 100644 (file)
--- a/arch/powerpc/include/asm/cputable.h
+++ b/arch/powerpc/include/asm/cputable.h
@@ -215,7 +215,7 @@ enum {
 #define CPU_FTR_DABRX                  LONG_ASM_CONST(0x0800000000000000)
 #define CPU_FTR_PMAO_BUG               LONG_ASM_CONST(0x1000000000000000)
 #define CPU_FTR_POWER9_DD1             LONG_ASM_CONST(0x4000000000000000)
-#define CPU_FTR_POWER9_DD20            LONG_ASM_CONST(0x8000000000000000)
+#define CPU_FTR_POWER9_DD2_1           LONG_ASM_CONST(0x8000000000000000)
 
 #ifndef __ASSEMBLY__
 
@@ -478,7 +478,8 @@ enum {
            CPU_FTR_ARCH_207S | CPU_FTR_TM_COMP | CPU_FTR_ARCH_300)
 #define CPU_FTRS_POWER9_DD1 ((CPU_FTRS_POWER9 | CPU_FTR_POWER9_DD1) & \
                             (~CPU_FTR_SAO))
-#define CPU_FTRS_POWER9_DD20 (CPU_FTRS_POWER9 | CPU_FTR_POWER9_DD20)
+#define CPU_FTRS_POWER9_DD2_0 CPU_FTRS_POWER9
+#define CPU_FTRS_POWER9_DD2_1 (CPU_FTRS_POWER9 | CPU_FTR_POWER9_DD2_1)
 #define CPU_FTRS_CELL  (CPU_FTR_USE_TB | CPU_FTR_LWSYNC | \
            CPU_FTR_PPCAS_ARCH_V2 | CPU_FTR_CTRL | \
            CPU_FTR_ALTIVEC_COMP | CPU_FTR_MMCRA | CPU_FTR_SMT | \
@@ -498,7 +499,7 @@ enum {
             CPU_FTRS_POWER6 | CPU_FTRS_POWER7 | CPU_FTRS_POWER8E | \
             CPU_FTRS_POWER8 | CPU_FTRS_POWER8_DD1 | CPU_FTRS_CELL | \
             CPU_FTRS_PA6T | CPU_FTR_VSX | CPU_FTRS_POWER9 | \
-            CPU_FTRS_POWER9_DD1 | CPU_FTRS_POWER9_DD20)
+            CPU_FTRS_POWER9_DD1 | CPU_FTRS_POWER9_DD2_1)
 #endif
 #else
 enum {

diff --git a/arch/powerpc/kernel/cputable.c b/arch/powerpc/kernel/cputable.c
index 171820190de7a1883a7e2703d6da914cd81fd24f..1350f49d81a847a318a619968682d92daec01d43 100644 (file)
--- a/arch/powerpc/kernel/cputable.c
+++ b/arch/powerpc/kernel/cputable.c
@@ -551,7 +551,7 @@ static struct cpu_spec __initdata cpu_specs[] = {
                .pvr_mask               = 0xffffefff,
                .pvr_value              = 0x004e0200,
                .cpu_name               = "POWER9 (raw)",
-               .cpu_features           = CPU_FTRS_POWER9_DD20,
+               .cpu_features           = CPU_FTRS_POWER9_DD2_0,
                .cpu_user_features      = COMMON_USER_POWER9,
                .cpu_user_features2     = COMMON_USER2_POWER9,
                .mmu_features           = MMU_FTRS_POWER9,
@@ -567,11 +567,11 @@ static struct cpu_spec __initdata cpu_specs[] = {
                .machine_check_early    = __machine_check_early_realmode_p9,
                .platform               = "power9",
        },
-       {       /* Power9 */
+       {       /* Power9 DD 2.1 or later (see DD2.0 above) */
                .pvr_mask               = 0xffff0000,
                .pvr_value              = 0x004e0000,
                .cpu_name               = "POWER9 (raw)",
-               .cpu_features           = CPU_FTRS_POWER9,
+               .cpu_features           = CPU_FTRS_POWER9_DD2_1,
                .cpu_user_features      = COMMON_USER_POWER9,
                .cpu_user_features2     = COMMON_USER2_POWER9,
                .mmu_features           = MMU_FTRS_POWER9,

diff --git a/arch/powerpc/kernel/dt_cpu_ftrs.c b/arch/powerpc/kernel/dt_cpu_ftrs.c
index 58e3b51de31c1f53af56afd597326ae7cb9bc543..602e0fde19b4a28ca505162dc07546bb2422b988 100644 (file)
--- a/arch/powerpc/kernel/dt_cpu_ftrs.c
+++ b/arch/powerpc/kernel/dt_cpu_ftrs.c
@@ -736,7 +736,7 @@ static __init void cpufeatures_cpu_quirks(void)
        if ((version & 0xffffff00) == 0x004e0100)
                cur_cpu_spec->cpu_features |= CPU_FTR_POWER9_DD1;
        else if ((version & 0xffffefff) == 0x004e0200)
-               cur_cpu_spec->cpu_features |= CPU_FTR_POWER9_DD20;
+               cur_cpu_spec->cpu_features &= ~CPU_FTR_POWER9_DD2_1;
 }
 
 static void __init cpufeatures_setup_finished(void)

diff --git a/arch/powerpc/kernel/idle_book3s.S b/arch/powerpc/kernel/idle_book3s.S
index 59657783d1d5b0b6b5e41cbc1c1b39881c4a051b..01e1c1997893368b6ba52034aeeb0bd513ede70c 100644 (file)
--- a/arch/powerpc/kernel/idle_book3s.S
+++ b/arch/powerpc/kernel/idle_book3s.S
@@ -357,13 +357,13 @@ power_enter_stop:
 .Lhandle_esl_ec_set:
 BEGIN_FTR_SECTION
        /*
-        * POWER9 DD2 can incorrectly set PMAO when waking up after a
-        * state-loss idle. Saving and restoring MMCR0 over idle is a
+        * POWER9 DD2.0 or earlier can incorrectly set PMAO when waking up after
+        * a state-loss idle. Saving and restoring MMCR0 over idle is a
         * workaround.
         */
        mfspr   r4,SPRN_MMCR0
        std     r4,_MMCR0(r1)
-END_FTR_SECTION_IFSET(CPU_FTR_POWER9_DD1 | CPU_FTR_POWER9_DD20)
+END_FTR_SECTION_IFCLR(CPU_FTR_POWER9_DD2_1)
 
 /*
  * Check if the requested state is a deep idle state.
@@ -554,7 +554,7 @@ BEGIN_FTR_SECTION
        ld      r1,PACAR1(r13)
        ld      r4,_MMCR0(r1)
        mtspr   SPRN_MMCR0,r4
-END_FTR_SECTION_IFSET(CPU_FTR_POWER9_DD1 | CPU_FTR_POWER9_DD20)
+END_FTR_SECTION_IFCLR(CPU_FTR_POWER9_DD2_1)
        mfspr   r4,SPRN_MMCRA
        ori     r4,r4,(1 << (63-60))
        mtspr   SPRN_MMCRA,r4