[PATCH V2] powerpc: Fix oops due to wrong access of lppaca on non virtualized platform

Commit 8e0b634b1327 ("powerpc/64s: Do not allocate lppaca if we are not
virtualized") removed allocation of lppaca on non virtualized platform. But with
CONFIG_PPC_SPLPAR enabled, we do access lppaca non-virtualized platform in some
code paths.

Fix this but adding runtime check for virtualized platform.

Fixes: 8e0b634b1327 ("powerpc/64s: Do not allocate lppaca if we are not virtualized")

Signed-off-by: Aneesh Kumar K.V <redacted>
---
Changes from V1:
* update commit summary

 arch/powerpc/include/asm/lppaca.h   | 3 +++
 arch/powerpc/include/asm/spinlock.h | 2 ++
 arch/powerpc/kernel/time.c          | 3 +++
 3 files changed, 8 insertions(+)

diff --git a/arch/powerpc/include/asm/lppaca.h b/arch/powerpc/include/asm/lppaca.h
index 65d589689f01..7c23ce8a5a4c 100644
--- a/arch/powerpc/include/asm/lppaca.h
+++ b/arch/powerpc/include/asm/lppaca.h

@@ -34,6 +34,7 @@
 #include <linux/threads.h>
 #include <asm/types.h>
 #include <asm/mmu.h>
+#include <asm/firmware.h>
 
 /*
  * The lppaca is the "virtual processor area" registered with the hypervisor,

@@ -114,6 +115,8 @@ struct lppaca {
 
 static inline bool lppaca_shared_proc(struct lppaca *l)
 {
+	if (!firmware_has_feature(FW_FEATURE_SPLPAR))
+		return false;
 	return !!(l->__old_status & LPPACA_OLD_SHARED_PROC);
 }
 

diff --git a/arch/powerpc/include/asm/spinlock.h b/arch/powerpc/include/asm/spinlock.h
index b9ebc3085fb7..72dc4ddc2972 100644
--- a/arch/powerpc/include/asm/spinlock.h
+++ b/arch/powerpc/include/asm/spinlock.h

@@ -56,6 +56,8 @@
 #define vcpu_is_preempted vcpu_is_preempted
 static inline bool vcpu_is_preempted(int cpu)
 {
+	if (!firmware_has_feature(FW_FEATURE_SPLPAR))
+		return false;
 	return !!(be32_to_cpu(lppaca_of(cpu).yield_count) & 1);
 }
 #endif

diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index f7d96a68ecaa..360e71d455cc 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c

@@ -266,6 +266,9 @@ void accumulate_stolen_time(void)
 
 static inline u64 calculate_stolen_time(u64 stop_tb)
 {
+	if (!firmware_has_feature(FW_FEATURE_SPLPAR))
+		return 0;
+
 	if (get_paca()->dtl_ridx != be64_to_cpu(get_lppaca()->dtl_idx))
 		return scan_dispatch_log(stop_tb);
 

-- 
2.14.3

On Mon,  2 Apr 2018 13:03:37 +0530
"Aneesh Kumar K.V" [off-list ref] wrote:

Commit 8e0b634b1327 ("powerpc/64s: Do not allocate lppaca if we are not
virtualized") removed allocation of lppaca on non virtualized platform. But with
CONFIG_PPC_SPLPAR enabled, we do access lppaca non-virtualized platform in some
code paths.

Fix this but adding runtime check for virtualized platform.

Fixes: 8e0b634b1327 ("powerpc/64s: Do not allocate lppaca if we are not virtualized")

Signed-off-by: Aneesh Kumar K.V <redacted>

Thanks, this looks good to me...

We should eventually clean this up. There's no need to pass in an lppaca
here AFAIKS. Is it even per-CPU, does it change dynamically? We could set
it up in a FW_FEATURE parameter at boot, which would could make some of
these tests cheaper.

On Mon, 2018-04-02 at 07:33:37 UTC, "Aneesh Kumar K.V" wrote:

Commit 8e0b634b1327 ("powerpc/64s: Do not allocate lppaca if we are not
virtualized") removed allocation of lppaca on non virtualized platform. But with
CONFIG_PPC_SPLPAR enabled, we do access lppaca non-virtualized platform in some
code paths.

Fix this but adding runtime check for virtualized platform.

Fixes: 8e0b634b1327 ("powerpc/64s: Do not allocate lppaca if we are not virtualized")

Signed-off-by: Aneesh Kumar K.V <redacted>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/a6201da34ff9366680e97392efd06a

cheers