* [PATCH v2] ACPI: CPPC: Fix access width used for PCC registers
@ 2024-04-11 21:23 Vanshidhar Konda
2024-04-11 22:07 ` Easwar Hariharan
0 siblings, 1 reply; 2+ messages in thread
From: Vanshidhar Konda @ 2024-04-11 21:23 UTC (permalink / raw
To: Jarred White, Easwar Hariharan
Cc: Rafael J . Wysocki, linux-acpi, linux-kernel, Vanshidhar Konda,
5 . 15+
commit 2f4a4d63a193be6fd530d180bb13c3592052904c modified
cpc_read/cpc_write to use access_width to read CPC registers. For PCC
registers the access width field in the ACPI register macro specifies
the PCC subspace id. For non-zero PCC subspace id the access width is
incorrectly treated as access width. This causes errors when reading
from PCC registers in the CPPC driver.
For PCC registers base the size of read/write on the bit width field.
The debug message in cpc_read/cpc_write is updated to print relevant
information for the address space type used to read the register.
Signed-off-by: Vanshidhar Konda <vanshikonda@os.amperecomputing.com>
Tested-by: Jarred White <jarredwhite@linux.microsoft.com>
Reviewed-by: Jarred White <jarredwhite@linux.microsoft.com>
Cc: 5.15+ <stable@vger.kernel.org> # 5.15+
---
When testing v6.9-rc1 kernel on AmpereOne system dmesg showed that
cpufreq policy had failed to initialize on some cores during boot because
cpufreq->get() always returned 0. On this system CPPC registers are in PCC
subspace index 2 that are 32 bits wide. With this patch the CPPC driver
interpreted the access width field as 16 bits, causing the register read
to roll over too quickly to provide valid values during frequency
computation.
v2:
- Use size variable in debug print message
- Use size instead of reg->bit_width for acpi_os_read_memory and
acpi_os_write_memory
drivers/acpi/cppc_acpi.c | 53 ++++++++++++++++++++++++++++------------
1 file changed, 37 insertions(+), 16 deletions(-)
diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index 4bfbe55553f4..a037e9d15f48 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -1002,14 +1002,14 @@ static int cpc_read(int cpu, struct cpc_register_resource *reg_res, u64 *val)
}
*val = 0;
+ size = GET_BIT_WIDTH(reg);
if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
- u32 width = GET_BIT_WIDTH(reg);
u32 val_u32;
acpi_status status;
status = acpi_os_read_port((acpi_io_address)reg->address,
- &val_u32, width);
+ &val_u32, size);
if (ACPI_FAILURE(status)) {
pr_debug("Error: Failed to read SystemIO port %llx\n",
reg->address);
@@ -1018,17 +1018,22 @@ static int cpc_read(int cpu, struct cpc_register_resource *reg_res, u64 *val)
*val = val_u32;
return 0;
- } else if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM && pcc_ss_id >= 0)
+ } else if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM && pcc_ss_id >= 0) {
+ /*
+ * For registers in PCC space, the register size is determined
+ * by the bit width field; the access size is used to indicate
+ * the PCC subspace id.
+ */
+ size = reg->bit_width;
vaddr = GET_PCC_VADDR(reg->address, pcc_ss_id);
+ }
else if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
vaddr = reg_res->sys_mem_vaddr;
else if (reg->space_id == ACPI_ADR_SPACE_FIXED_HARDWARE)
return cpc_read_ffh(cpu, reg, val);
else
return acpi_os_read_memory((acpi_physical_address)reg->address,
- val, reg->bit_width);
-
- size = GET_BIT_WIDTH(reg);
+ val, size);
switch (size) {
case 8:
@@ -1044,8 +1049,13 @@ static int cpc_read(int cpu, struct cpc_register_resource *reg_res, u64 *val)
*val = readq_relaxed(vaddr);
break;
default:
- pr_debug("Error: Cannot read %u bit width from PCC for ss: %d\n",
- reg->bit_width, pcc_ss_id);
+ if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
+ pr_debug("Error: Cannot read %u width from for system memory: 0x%llx\n",
+ size, reg->address);
+ } else if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM) {
+ pr_debug("Error: Cannot read %u bit width to PCC for ss: %d\n",
+ size, pcc_ss_id);
+ }
return -EFAULT;
}
@@ -1063,12 +1073,13 @@ static int cpc_write(int cpu, struct cpc_register_resource *reg_res, u64 val)
int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
struct cpc_reg *reg = ®_res->cpc_entry.reg;
+ size = GET_BIT_WIDTH(reg);
+
if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
- u32 width = GET_BIT_WIDTH(reg);
acpi_status status;
status = acpi_os_write_port((acpi_io_address)reg->address,
- (u32)val, width);
+ (u32)val, size);
if (ACPI_FAILURE(status)) {
pr_debug("Error: Failed to write SystemIO port %llx\n",
reg->address);
@@ -1076,17 +1087,22 @@ static int cpc_write(int cpu, struct cpc_register_resource *reg_res, u64 val)
}
return 0;
- } else if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM && pcc_ss_id >= 0)
+ } else if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM && pcc_ss_id >= 0) {
+ /*
+ * For registers in PCC space, the register size is determined
+ * by the bit width field; the access size is used to indicate
+ * the PCC subspace id.
+ */
+ size = reg->bit_width;
vaddr = GET_PCC_VADDR(reg->address, pcc_ss_id);
+ }
else if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
vaddr = reg_res->sys_mem_vaddr;
else if (reg->space_id == ACPI_ADR_SPACE_FIXED_HARDWARE)
return cpc_write_ffh(cpu, reg, val);
else
return acpi_os_write_memory((acpi_physical_address)reg->address,
- val, reg->bit_width);
-
- size = GET_BIT_WIDTH(reg);
+ val, size);
if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
val = MASK_VAL(reg, val);
@@ -1105,8 +1121,13 @@ static int cpc_write(int cpu, struct cpc_register_resource *reg_res, u64 val)
writeq_relaxed(val, vaddr);
break;
default:
- pr_debug("Error: Cannot write %u bit width to PCC for ss: %d\n",
- reg->bit_width, pcc_ss_id);
+ if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
+ pr_debug("Error: Cannot write %u width from for system memory: 0x%llx\n",
+ size, reg->address);
+ } else if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM) {
+ pr_debug("Error: Cannot write %u bit width to PCC for ss: %d\n",
+ size, pcc_ss_id);
+ }
ret_val = -EFAULT;
break;
}
--
2.43.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v2] ACPI: CPPC: Fix access width used for PCC registers
2024-04-11 21:23 [PATCH v2] ACPI: CPPC: Fix access width used for PCC registers Vanshidhar Konda
@ 2024-04-11 22:07 ` Easwar Hariharan
0 siblings, 0 replies; 2+ messages in thread
From: Easwar Hariharan @ 2024-04-11 22:07 UTC (permalink / raw
To: Vanshidhar Konda, Jarred White
Cc: Rafael J . Wysocki, linux-acpi, linux-kernel, 5 . 15+
On 4/11/2024 2:23 PM, Vanshidhar Konda wrote:
> commit 2f4a4d63a193be6fd530d180bb13c3592052904c modified
> cpc_read/cpc_write to use access_width to read CPC registers. For PCC
> registers the access width field in the ACPI register macro specifies
> the PCC subspace id. For non-zero PCC subspace id the access width is
> incorrectly treated as access width. This causes errors when reading
> from PCC registers in the CPPC driver.
>
> For PCC registers base the size of read/write on the bit width field.
> The debug message in cpc_read/cpc_write is updated to print relevant
> information for the address space type used to read the register.
>
> Signed-off-by: Vanshidhar Konda <vanshikonda@os.amperecomputing.com>
> Tested-by: Jarred White <jarredwhite@linux.microsoft.com>
> Reviewed-by: Jarred White <jarredwhite@linux.microsoft.com>
> Cc: 5.15+ <stable@vger.kernel.org> # 5.15+
> ---
>
> When testing v6.9-rc1 kernel on AmpereOne system dmesg showed that
> cpufreq policy had failed to initialize on some cores during boot because
> cpufreq->get() always returned 0. On this system CPPC registers are in PCC
> subspace index 2 that are 32 bits wide. With this patch the CPPC driver
> interpreted the access width field as 16 bits, causing the register read
> to roll over too quickly to provide valid values during frequency
> computation.
>
> v2:
> - Use size variable in debug print message
> - Use size instead of reg->bit_width for acpi_os_read_memory and
> acpi_os_write_memory
>
> drivers/acpi/cppc_acpi.c | 53 ++++++++++++++++++++++++++++------------
> 1 file changed, 37 insertions(+), 16 deletions(-)
Thanks for adding the CC: stable tag. Couple of nits, assuming those are fixed:
Reviewed-by: Easwar Hariharan <eahariha@linux.microsoft.com>
>
> diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
> index 4bfbe55553f4..a037e9d15f48 100644
> --- a/drivers/acpi/cppc_acpi.c
> +++ b/drivers/acpi/cppc_acpi.c
> @@ -1002,14 +1002,14 @@ static int cpc_read(int cpu, struct cpc_register_resource *reg_res, u64 *val)
> }
>
> *val = 0;
> + size = GET_BIT_WIDTH(reg);
>
> if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
> - u32 width = GET_BIT_WIDTH(reg);
> u32 val_u32;
> acpi_status status;
>
> status = acpi_os_read_port((acpi_io_address)reg->address,
> - &val_u32, width);
> + &val_u32, size);
> if (ACPI_FAILURE(status)) {
> pr_debug("Error: Failed to read SystemIO port %llx\n",
> reg->address);
> @@ -1018,17 +1018,22 @@ static int cpc_read(int cpu, struct cpc_register_resource *reg_res, u64 *val)
>
> *val = val_u32;
> return 0;
> - } else if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM && pcc_ss_id >= 0)
> + } else if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM && pcc_ss_id >= 0) {
> + /*
> + * For registers in PCC space, the register size is determined
> + * by the bit width field; the access size is used to indicate
> + * the PCC subspace id.
> + */
> + size = reg->bit_width;
> vaddr = GET_PCC_VADDR(reg->address, pcc_ss_id);
> + }
> else if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
> vaddr = reg_res->sys_mem_vaddr;
> else if (reg->space_id == ACPI_ADR_SPACE_FIXED_HARDWARE)
> return cpc_read_ffh(cpu, reg, val);
> else
> return acpi_os_read_memory((acpi_physical_address)reg->address,
> - val, reg->bit_width);
> -
> - size = GET_BIT_WIDTH(reg);
> + val, size);
>
> switch (size) {
> case 8:
> @@ -1044,8 +1049,13 @@ static int cpc_read(int cpu, struct cpc_register_resource *reg_res, u64 *val)
> *val = readq_relaxed(vaddr);
> break;
> default:
> - pr_debug("Error: Cannot read %u bit width from PCC for ss: %d\n",
> - reg->bit_width, pcc_ss_id);
> + if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
> + pr_debug("Error: Cannot read %u width from for system memory: 0x%llx\n",
> + size, reg->address);
Nit: from for? There might be a missing word there, or just an extra. Ditto for cpc_write() below.
> + } else if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM) {
> + pr_debug("Error: Cannot read %u bit width to PCC for ss: %d\n",
> + size, pcc_ss_id);
> + }
> return -EFAULT;
> }
>
> @@ -1063,12 +1073,13 @@ static int cpc_write(int cpu, struct cpc_register_resource *reg_res, u64 val)
> int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
> struct cpc_reg *reg = ®_res->cpc_entry.reg;
>
> + size = GET_BIT_WIDTH(reg);
> +
> if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
> - u32 width = GET_BIT_WIDTH(reg);
> acpi_status status;
>
> status = acpi_os_write_port((acpi_io_address)reg->address,
> - (u32)val, width);
> + (u32)val, size);
> if (ACPI_FAILURE(status)) {
> pr_debug("Error: Failed to write SystemIO port %llx\n",
> reg->address);
> @@ -1076,17 +1087,22 @@ static int cpc_write(int cpu, struct cpc_register_resource *reg_res, u64 val)
> }
>
> return 0;
> - } else if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM && pcc_ss_id >= 0)
> + } else if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM && pcc_ss_id >= 0) {
> + /*
> + * For registers in PCC space, the register size is determined
> + * by the bit width field; the access size is used to indicate
> + * the PCC subspace id.
> + */
> + size = reg->bit_width;
> vaddr = GET_PCC_VADDR(reg->address, pcc_ss_id);
> + }
> else if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
> vaddr = reg_res->sys_mem_vaddr;
> else if (reg->space_id == ACPI_ADR_SPACE_FIXED_HARDWARE)
> return cpc_write_ffh(cpu, reg, val);
> else
> return acpi_os_write_memory((acpi_physical_address)reg->address,
> - val, reg->bit_width);
> -
> - size = GET_BIT_WIDTH(reg);
> + val, size);
>
> if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
> val = MASK_VAL(reg, val);
> @@ -1105,8 +1121,13 @@ static int cpc_write(int cpu, struct cpc_register_resource *reg_res, u64 val)
> writeq_relaxed(val, vaddr);
> break;
> default:
> - pr_debug("Error: Cannot write %u bit width to PCC for ss: %d\n",
> - reg->bit_width, pcc_ss_id);
> + if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
> + pr_debug("Error: Cannot write %u width from for system memory: 0x%llx\n",
> + size, reg->address);
> + } else if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM) {
> + pr_debug("Error: Cannot write %u bit width to PCC for ss: %d\n",
> + size, pcc_ss_id);
> + }
> ret_val = -EFAULT;
> break;
> }
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