Merge tag 'x86_misc_for_v6.11_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull misc x86 updates from Borislav Petkov:

 - Make error checking of AMD SMN accesses more robust in the callers as
   they're the only ones who can interpret the results properly

 - The usual cleanups and fixes, left and right

* tag 'x86_misc_for_v6.11_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/kmsan: Fix hook for unaligned accesses
  x86/platform/iosf_mbi: Convert PCIBIOS_* return codes to errnos
  x86/pci/xen: Fix PCIBIOS_* return code handling
  x86/pci/intel_mid_pci: Fix PCIBIOS_* return code handling
  x86/of: Return consistent error type from x86_of_pci_irq_enable()
  hwmon: (k10temp) Rename _data variable
  hwmon: (k10temp) Remove unused HAVE_TDIE() macro
  hwmon: (k10temp) Reduce k10temp_get_ccd_support() parameters
  hwmon: (k10temp) Define a helper function to read CCD temperature
  x86/amd_nb: Enhance SMN access error checking
  hwmon: (k10temp) Check return value of amd_smn_read()
  EDAC/amd64: Check return value of amd_smn_read()
  EDAC/amd64: Remove unused register accesses
  tools/x86/kcpuid: Add missing dir via Makefile
  x86, arm: Add missing license tag to syscall tables files

2 files changed, 40 insertions, 6 deletions

diff --git a/arch/x86/kernel/amd_nb.c b/arch/x86/kernel/amd_nb.c
index 027a8c7a2c9e..059e5c16af05 100644
--- a/arch/x86/kernel/amd_nb.c
+++ b/arch/x86/kernel/amd_nb.c
@@ -180,6 +180,43 @@ static struct pci_dev *next_northbridge(struct pci_dev *dev,
 	return dev;
 }
 
+/*
+ * SMN accesses may fail in ways that are difficult to detect here in the called
+ * functions amd_smn_read() and amd_smn_write(). Therefore, callers must do
+ * their own checking based on what behavior they expect.
+ *
+ * For SMN reads, the returned value may be zero if the register is Read-as-Zero.
+ * Or it may be a "PCI Error Response", e.g. all 0xFFs. The "PCI Error Response"
+ * can be checked here, and a proper error code can be returned.
+ *
+ * But the Read-as-Zero response cannot be verified here. A value of 0 may be
+ * correct in some cases, so callers must check that this correct is for the
+ * register/fields they need.
+ *
+ * For SMN writes, success can be determined through a "write and read back"
+ * However, this is not robust when done here.
+ *
+ * Possible issues:
+ *
+ * 1) Bits that are "Write-1-to-Clear". In this case, the read value should
+ *    *not* match the write value.
+ *
+ * 2) Bits that are "Read-as-Zero"/"Writes-Ignored". This information cannot be
+ *    known here.
+ *
+ * 3) Bits that are "Reserved / Set to 1". Ditto above.
+ *
+ * Callers of amd_smn_write() should do the "write and read back" check
+ * themselves, if needed.
+ *
+ * For #1, they can see if their target bits got cleared.
+ *
+ * For #2 and #3, they can check if their target bits got set as intended.
+ *
+ * This matches what is done for RDMSR/WRMSR. As long as there's no #GP, then
+ * the operation is considered a success, and the caller does their own
+ * checking.
+ */
 static int __amd_smn_rw(u16 node, u32 address, u32 *value, bool write)
 {
 	struct pci_dev *root;
@@ -202,9 +239,6 @@ static int __amd_smn_rw(u16 node, u32 address, u32 *value, bool write)
 
 	err = (write ? pci_write_config_dword(root, 0x64, *value)
 		     : pci_read_config_dword(root, 0x64, value));
-	if (err)
-		pr_warn("Error %s SMN address 0x%x.\n",
-			(write ? "writing to" : "reading from"), address);
 
 out_unlock:
 	mutex_unlock(&smn_mutex);
@@ -213,7 +247,7 @@ out:
 	return err;
 }
 
-int amd_smn_read(u16 node, u32 address, u32 *value)
+int __must_check amd_smn_read(u16 node, u32 address, u32 *value)
 {
 	int err = __amd_smn_rw(node, address, value, false);
 
@@ -226,7 +260,7 @@ int amd_smn_read(u16 node, u32 address, u32 *value)
 }
 EXPORT_SYMBOL_GPL(amd_smn_read);
 
-int amd_smn_write(u16 node, u32 address, u32 value)
+int __must_check amd_smn_write(u16 node, u32 address, u32 value)
 {
 	return __amd_smn_rw(node, address, &value, true);
 }
diff --git a/arch/x86/kernel/devicetree.c b/arch/x86/kernel/devicetree.c
index 8e3c53b4d070..64280879c68c 100644
--- a/arch/x86/kernel/devicetree.c
+++ b/arch/x86/kernel/devicetree.c
@@ -83,7 +83,7 @@ static int x86_of_pci_irq_enable(struct pci_dev *dev)
 
 	ret = pci_read_config_byte(dev, PCI_INTERRUPT_PIN, &pin);
 	if (ret)
-		return ret;
+		return pcibios_err_to_errno(ret);
 	if (!pin)
 		return 0;