[tip: x86/cpu] x86/umip: Downgrade warning messages to debug loglevel

[tip-bot2 for Borislav Petkov]

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

Commit-ID:     1eefe7a85678a056951cd9efb09820c1b0a1b4da
Gitweb:        https://git.kernel.org/tip/1eefe7a85678a056951cd9efb09820c1b0a1b4da
Author:        Borislav Petkov <bp@xxxxxxx>
AuthorDate:    Wed, 15 Sep 2021 16:39:18 +02:00
Committer:     Borislav Petkov <bp@xxxxxxx>
CommitterDate: Thu, 23 Sep 2021 16:30:11 +02:00

x86/umip: Downgrade warning messages to debug loglevel

After four years in the wild, those have not fullfilled their
initial purpose of pushing people to fix their software to not use
UMIP-emulated instructions, and to warn users about the degraded
emulation performance.

Yet, the only thing that "degrades" performance is overflowing dmesg
with those:

  [Di Sep  7 00:24:05 2021] umip_printk: 1345 callbacks suppressed
  [Di Sep  7 00:24:05 2021] umip: someapp.exe[29231] ip:14064cdba sp:11b7c0: SIDT instruction cannot be used by applications.
  [Di Sep  7 00:24:05 2021] umip: someapp.exe[29231] ip:14064cdba sp:11b7c0: For now, expensive software emulation returns the result.
  ...
  [Di Sep  7 00:26:06 2021] umip_printk: 2227 callbacks suppressed
  [Di Sep  7 00:26:06 2021] umip: someapp.exe[29231] ip:14064cdba sp:11b940: SIDT instruction cannot be used by applications.

and users don't really care about that - they just want to play their
games in wine.

So convert those to debug loglevel - in case someone is still interested
in them, someone can boot with "debug" on the kernel cmdline.

Reported-by: Marcus Rückert <mrueckert@xxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Link: https://lkml.kernel.org/r/20210907200454.30458-1-bp@xxxxxxxxx
---
 arch/x86/kernel/umip.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/umip.c b/arch/x86/kernel/umip.c
index 576b47e..5a4b213 100644
--- a/arch/x86/kernel/umip.c
+++ b/arch/x86/kernel/umip.c
@@ -92,8 +92,8 @@ static const char * const umip_insns[5] = {
 
 #define umip_pr_err(regs, fmt, ...) \
 	umip_printk(regs, KERN_ERR, fmt, ##__VA_ARGS__)
-#define umip_pr_warn(regs, fmt, ...) \
-	umip_printk(regs, KERN_WARNING, fmt,  ##__VA_ARGS__)
+#define umip_pr_debug(regs, fmt, ...) \
+	umip_printk(regs, KERN_DEBUG, fmt,  ##__VA_ARGS__)
 
 /**
  * umip_printk() - Print a rate-limited message
@@ -361,10 +361,10 @@ bool fixup_umip_exception(struct pt_regs *regs)
 	if (umip_inst < 0)
 		return false;
 
-	umip_pr_warn(regs, "%s instruction cannot be used by applications.\n",
+	umip_pr_debug(regs, "%s instruction cannot be used by applications.\n",
 			umip_insns[umip_inst]);
 
-	umip_pr_warn(regs, "For now, expensive software emulation returns the result.\n");
+	umip_pr_debug(regs, "For now, expensive software emulation returns the result.\n");
 
 	if (emulate_umip_insn(&insn, umip_inst, dummy_data, &dummy_data_size,
 			      user_64bit_mode(regs)))