[tip: x86/urgent] x86/mm: Avoid incomplete Global INVLPG flushes

[tip-bot2 for Dave Hansen]

The following commit has been merged into the x86/urgent branch of tip:

Commit-ID:     ce0b15d11ad837fbacc5356941712218e38a0a83
Gitweb:        https://git.kernel.org/tip/ce0b15d11ad837fbacc5356941712218e38a0a83
Author:        Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
AuthorDate:    Tue, 16 May 2023 12:24:25 -07:00
Committer:     Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
CommitterDate: Wed, 17 May 2023 08:55:02 -07:00

x86/mm: Avoid incomplete Global INVLPG flushes

The INVLPG instruction is used to invalidate TLB entries for a
specified virtual address.  When PCIDs are enabled, INVLPG is supposed
to invalidate TLB entries for the specified address for both the
current PCID *and* Global entries.  (Note: Only kernel mappings set
Global=1.)

Unfortunately, some INVLPG implementations can leave Global
translations unflushed when PCIDs are enabled.

As a workaround, never enable PCIDs on affected processors.

I expect there to eventually be microcode mitigations to replace this
software workaround.  However, the exact version numbers where that
will happen are not known today.  Once the version numbers are set in
stone, the processor list can be tweaked to only disable PCIDs on
affected processors with affected microcode.

Note: if anyone wants a quick fix that doesn't require patching, just
stick 'nopcid' on your kernel command-line.

Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
 arch/x86/mm/init.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 3cdac0f..8192452 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -9,6 +9,7 @@
 #include <linux/sched/task.h>
 
 #include <asm/set_memory.h>
+#include <asm/cpu_device_id.h>
 #include <asm/e820/api.h>
 #include <asm/init.h>
 #include <asm/page.h>
@@ -261,6 +262,24 @@ static void __init probe_page_size_mask(void)
 	}
 }
 
+#define INTEL_MATCH(_model) { .vendor  = X86_VENDOR_INTEL,	\
+			      .family  = 6,			\
+			      .model = _model,			\
+			    }
+/*
+ * INVLPG may not properly flush Global entries
+ * on these CPUs when PCIDs are enabled.
+ */
+static const struct x86_cpu_id invlpg_miss_ids[] = {
+	INTEL_MATCH(INTEL_FAM6_ALDERLAKE   ),
+	INTEL_MATCH(INTEL_FAM6_ALDERLAKE_L ),
+	INTEL_MATCH(INTEL_FAM6_ALDERLAKE_N ),
+	INTEL_MATCH(INTEL_FAM6_RAPTORLAKE  ),
+	INTEL_MATCH(INTEL_FAM6_RAPTORLAKE_P),
+	INTEL_MATCH(INTEL_FAM6_RAPTORLAKE_S),
+	{}
+};
+
 static void setup_pcid(void)
 {
 	if (!IS_ENABLED(CONFIG_X86_64))
@@ -269,6 +288,12 @@ static void setup_pcid(void)
 	if (!boot_cpu_has(X86_FEATURE_PCID))
 		return;
 
+	if (x86_match_cpu(invlpg_miss_ids)) {
+		pr_info("Incomplete global flushes, disabling PCID");
+		setup_clear_cpu_cap(X86_FEATURE_PCID);
+		return;
+	}
+
 	if (boot_cpu_has(X86_FEATURE_PGE)) {
 		/*
 		 * This can't be cr4_set_bits_and_update_boot() -- the