This is a note to let you know that I've just added the patch titled
x86/mm: Avoid incomplete Global INVLPG flushes
to the 4.19-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:
x86-mm-avoid-incomplete-global-invlpg-flushes.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From ce0b15d11ad837fbacc5356941712218e38a0a83 Mon Sep 17 00:00:00 2001
From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Date: Tue, 16 May 2023 12:24:25 -0700
Subject: x86/mm: Avoid incomplete Global INVLPG flushes
From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
commit ce0b15d11ad837fbacc5356941712218e38a0a83 upstream.
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
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/mm/init.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -9,6 +9,7 @@
#include <linux/kmemleak.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>
@@ -207,6 +208,24 @@ static void __init probe_page_size_mask(
}
}
+#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))
@@ -215,6 +234,12 @@ 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
Patches currently in stable-queue which might be from dave.hansen@xxxxxxxxxxxxxxx are
queue-4.19/x86-mm-avoid-incomplete-global-invlpg-flushes.patch
