Patch "ACPI: CPPC: Use access_width over bit_width for system memory accesses" has been added to the 6.7-stable tree

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This is a note to let you know that I've just added the patch titled

    ACPI: CPPC: Use access_width over bit_width for system memory accesses

to the 6.7-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     acpi-cppc-use-access_width-over-bit_width-for-system.patch
and it can be found in the queue-6.7 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 9e9952e74ab1e68d198cae092c5e8bc1fa8a00c7
Author: Jarred White <jarredwhite@xxxxxxxxxxxxxxxxxxx>
Date:   Fri Mar 1 11:25:59 2024 -0800

    ACPI: CPPC: Use access_width over bit_width for system memory accesses
    
    [ Upstream commit 2f4a4d63a193be6fd530d180bb13c3592052904c ]
    
    To align with ACPI 6.3+, since bit_width can be any 8-bit value, it
    cannot be depended on to be always on a clean 8b boundary. This was
    uncovered on the Cobalt 100 platform.
    
    SError Interrupt on CPU26, code 0xbe000011 -- SError
     CPU: 26 PID: 1510 Comm: systemd-udevd Not tainted 5.15.2.1-13 #1
     Hardware name: MICROSOFT CORPORATION, BIOS MICROSOFT CORPORATION
     pstate: 62400009 (nZCv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
     pc : cppc_get_perf_caps+0xec/0x410
     lr : cppc_get_perf_caps+0xe8/0x410
     sp : ffff8000155ab730
     x29: ffff8000155ab730 x28: ffff0080139d0038 x27: ffff0080139d0078
     x26: 0000000000000000 x25: ffff0080139d0058 x24: 00000000ffffffff
     x23: ffff0080139d0298 x22: ffff0080139d0278 x21: 0000000000000000
     x20: ffff00802b251910 x19: ffff0080139d0000 x18: ffffffffffffffff
     x17: 0000000000000000 x16: ffffdc7e111bad04 x15: ffff00802b251008
     x14: ffffffffffffffff x13: ffff013f1fd63300 x12: 0000000000000006
     x11: ffffdc7e128f4420 x10: 0000000000000000 x9 : ffffdc7e111badec
     x8 : ffff00802b251980 x7 : 0000000000000000 x6 : ffff0080139d0028
     x5 : 0000000000000000 x4 : ffff0080139d0018 x3 : 00000000ffffffff
     x2 : 0000000000000008 x1 : ffff8000155ab7a0 x0 : 0000000000000000
     Kernel panic - not syncing: Asynchronous SError Interrupt
     CPU: 26 PID: 1510 Comm: systemd-udevd Not tainted
    5.15.2.1-13 #1
     Hardware name: MICROSOFT CORPORATION, BIOS MICROSOFT CORPORATION
     Call trace:
      dump_backtrace+0x0/0x1e0
      show_stack+0x24/0x30
      dump_stack_lvl+0x8c/0xb8
      dump_stack+0x18/0x34
      panic+0x16c/0x384
      add_taint+0x0/0xc0
      arm64_serror_panic+0x7c/0x90
      arm64_is_fatal_ras_serror+0x34/0xa4
      do_serror+0x50/0x6c
      el1h_64_error_handler+0x40/0x74
      el1h_64_error+0x7c/0x80
      cppc_get_perf_caps+0xec/0x410
      cppc_cpufreq_cpu_init+0x74/0x400 [cppc_cpufreq]
      cpufreq_online+0x2dc/0xa30
      cpufreq_add_dev+0xc0/0xd4
      subsys_interface_register+0x134/0x14c
      cpufreq_register_driver+0x1b0/0x354
      cppc_cpufreq_init+0x1a8/0x1000 [cppc_cpufreq]
      do_one_initcall+0x50/0x250
      do_init_module+0x60/0x27c
      load_module+0x2300/0x2570
      __do_sys_finit_module+0xa8/0x114
      __arm64_sys_finit_module+0x2c/0x3c
      invoke_syscall+0x78/0x100
      el0_svc_common.constprop.0+0x180/0x1a0
      do_el0_svc+0x84/0xa0
      el0_svc+0x2c/0xc0
      el0t_64_sync_handler+0xa4/0x12c
      el0t_64_sync+0x1a4/0x1a8
    
    Instead, use access_width to determine the size and use the offset and
    width to shift and mask the bits to read/write out. Make sure to add a
    check for system memory since pcc redefines the access_width to
    subspace id.
    
    If access_width is not set, then fall back to using bit_width.
    
    Signed-off-by: Jarred White <jarredwhite@xxxxxxxxxxxxxxxxxxx>
    Reviewed-by: Easwar Hariharan <eahariha@xxxxxxxxxxxxxxxxxxx>
    Cc: 5.15+ <stable@xxxxxxxxxxxxxxx> # 5.15+
    [ rjw: Subject and changelog edits, comment adjustments ]
    Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index 7ff269a78c208..bcc5d8f5bb5ee 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -163,6 +163,13 @@ show_cppc_data(cppc_get_perf_caps, cppc_perf_caps, nominal_freq);
 show_cppc_data(cppc_get_perf_ctrs, cppc_perf_fb_ctrs, reference_perf);
 show_cppc_data(cppc_get_perf_ctrs, cppc_perf_fb_ctrs, wraparound_time);
 
+/* Check for valid access_width, otherwise, fallback to using bit_width */
+#define GET_BIT_WIDTH(reg) ((reg)->access_width ? (8 << ((reg)->access_width - 1)) : (reg)->bit_width)
+
+/* Shift and apply the mask for CPC reads/writes */
+#define MASK_VAL(reg, val) ((val) >> ((reg)->bit_offset & 			\
+					GENMASK(((reg)->bit_width), 0)))
+
 static ssize_t show_feedback_ctrs(struct kobject *kobj,
 		struct kobj_attribute *attr, char *buf)
 {
@@ -777,6 +784,7 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
 			} else if (gas_t->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
 				if (gas_t->address) {
 					void __iomem *addr;
+					size_t access_width;
 
 					if (!osc_cpc_flexible_adr_space_confirmed) {
 						pr_debug("Flexible address space capability not supported\n");
@@ -784,7 +792,8 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
 							goto out_free;
 					}
 
-					addr = ioremap(gas_t->address, gas_t->bit_width/8);
+					access_width = GET_BIT_WIDTH(gas_t) / 8;
+					addr = ioremap(gas_t->address, access_width);
 					if (!addr)
 						goto out_free;
 					cpc_ptr->cpc_regs[i-2].sys_mem_vaddr = addr;
@@ -980,6 +989,7 @@ int __weak cpc_write_ffh(int cpunum, struct cpc_reg *reg, u64 val)
 static int cpc_read(int cpu, struct cpc_register_resource *reg_res, u64 *val)
 {
 	void __iomem *vaddr = NULL;
+	int size;
 	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
 	struct cpc_reg *reg = &reg_res->cpc_entry.reg;
 
@@ -991,7 +1001,7 @@ static int cpc_read(int cpu, struct cpc_register_resource *reg_res, u64 *val)
 	*val = 0;
 
 	if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
-		u32 width = 8 << (reg->access_width - 1);
+		u32 width = GET_BIT_WIDTH(reg);
 		u32 val_u32;
 		acpi_status status;
 
@@ -1015,7 +1025,9 @@ static int cpc_read(int cpu, struct cpc_register_resource *reg_res, u64 *val)
 		return acpi_os_read_memory((acpi_physical_address)reg->address,
 				val, reg->bit_width);
 
-	switch (reg->bit_width) {
+	size = GET_BIT_WIDTH(reg);
+
+	switch (size) {
 	case 8:
 		*val = readb_relaxed(vaddr);
 		break;
@@ -1034,18 +1046,22 @@ static int cpc_read(int cpu, struct cpc_register_resource *reg_res, u64 *val)
 		return -EFAULT;
 	}
 
+	if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
+		*val = MASK_VAL(reg, *val);
+
 	return 0;
 }
 
 static int cpc_write(int cpu, struct cpc_register_resource *reg_res, u64 val)
 {
 	int ret_val = 0;
+	int size;
 	void __iomem *vaddr = NULL;
 	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
 	struct cpc_reg *reg = &reg_res->cpc_entry.reg;
 
 	if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
-		u32 width = 8 << (reg->access_width - 1);
+		u32 width = GET_BIT_WIDTH(reg);
 		acpi_status status;
 
 		status = acpi_os_write_port((acpi_io_address)reg->address,
@@ -1067,7 +1083,12 @@ static int cpc_write(int cpu, struct cpc_register_resource *reg_res, u64 val)
 		return acpi_os_write_memory((acpi_physical_address)reg->address,
 				val, reg->bit_width);
 
-	switch (reg->bit_width) {
+	size = GET_BIT_WIDTH(reg);
+
+	if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
+		val = MASK_VAL(reg, val);
+
+	switch (size) {
 	case 8:
 		writeb_relaxed(val, vaddr);
 		break;




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