[PATCH 0/2] A few fixes to DTL buffer access over debugfs

[PATCH 0/2] A few fixes to DTL buffer access over debugfs

[Naveen N. Rao]

Two trivial fixes to DTL buffer access over debugfs when 
CONFIG_VIRT_CPU_ACCOUNTING_NATIVE is not set.

- Naveen

Naveen N. Rao (2):
  powerpc/pseries: Fix DTL buffer registration
  powerpc/pseries: Fix how we iterate over the DTL entries

 arch/powerpc/platforms/pseries/dtl.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

-- 
2.19.0

[PATCH 1/2] powerpc/pseries: Fix DTL buffer registration

[Naveen N. Rao]

When CONFIG_VIRT_CPU_ACCOUNTING_NATIVE is not set, we register the DTL
buffer for a cpu when the associated file under powerpc/dtl in debugfs
is opened. When doing so, we need to set the size of the buffer being
registered in the second u32 word of the buffer. This needs to be in big
endian, but we are not doing the conversion resulting in the below error
showing up in dmesg:

	dtl_start: DTL registration for cpu 0 (hw 0) failed with -4

Fix this in the obvious manner.

Fixes: 7c105b63bd98 ("powerpc: Add CONFIG_CPU_LITTLE_ENDIAN kernel config option.")
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
---
 arch/powerpc/platforms/pseries/dtl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/pseries/dtl.c b/arch/powerpc/platforms/pseries/dtl.c
index 18014cdeb590..c762689e0eb3 100644
--- a/arch/powerpc/platforms/pseries/dtl.c
+++ b/arch/powerpc/platforms/pseries/dtl.c
@@ -149,7 +149,7 @@ static int dtl_start(struct dtl *dtl)
 
 	/* Register our dtl buffer with the hypervisor. The HV expects the
 	 * buffer size to be passed in the second word of the buffer */
-	((u32 *)dtl->buf)[1] = DISPATCH_LOG_BYTES;
+	((u32 *)dtl->buf)[1] = cpu_to_be32(DISPATCH_LOG_BYTES);
 
 	hwcpu = get_hard_smp_processor_id(dtl->cpu);
 	addr = __pa(dtl->buf);
-- 
2.19.0

Re: [1/2] powerpc/pseries: Fix DTL buffer registration

[Michael Ellerman]

On Thu, 2018-09-27 at 08:10:57 UTC, "Naveen N. Rao" wrote:
> When CONFIG_VIRT_CPU_ACCOUNTING_NATIVE is not set, we register the DTL
> buffer for a cpu when the associated file under powerpc/dtl in debugfs
> is opened. When doing so, we need to set the size of the buffer being
> registered in the second u32 word of the buffer. This needs to be in big
> endian, but we are not doing the conversion resulting in the below error
> showing up in dmesg:
> 
> 	dtl_start: DTL registration for cpu 0 (hw 0) failed with -4
> 
> Fix this in the obvious manner.
> 
> Fixes: 7c105b63bd98 ("powerpc: Add CONFIG_CPU_LITTLE_ENDIAN kernel config option.")
> Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>

Series applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/db787af1b8a6b4be428ee2ea7d409d

cheers

[PATCH 2/2] powerpc/pseries: Fix how we iterate over the DTL entries

[Naveen N. Rao]

When CONFIG_VIRT_CPU_ACCOUNTING_NATIVE is not set, we look up dtl_idx in
the lppaca to determine the number of entries in the buffer. Since
lppaca is in big endian, we need to do an endian conversion before using
this in our calculation to determine the number of entries in the
buffer. Without this, we do not iterate over the existing entries in the
DTL buffer properly.

Fixes: 7c105b63bd98 ("powerpc: Add CONFIG_CPU_LITTLE_ENDIAN kernel config option.")
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
---
 arch/powerpc/platforms/pseries/dtl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/pseries/dtl.c b/arch/powerpc/platforms/pseries/dtl.c
index c762689e0eb3..ef6595153642 100644
--- a/arch/powerpc/platforms/pseries/dtl.c
+++ b/arch/powerpc/platforms/pseries/dtl.c
@@ -184,7 +184,7 @@ static void dtl_stop(struct dtl *dtl)
 
 static u64 dtl_current_index(struct dtl *dtl)
 {
-	return lppaca_of(dtl->cpu).dtl_idx;
+	return be64_to_cpu(lppaca_of(dtl->cpu).dtl_idx);
 }
 #endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
 
-- 
2.19.0