Messages in this thread | | | Date | Mon, 13 Sep 2021 14:45:03 -0700 | From | Ricardo Neri <> | Subject | Re: [PATCH] x86/umip: Add a umip= cmdline switch |
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On Tue, Sep 07, 2021 at 10:04:54PM +0200, Borislav Petkov wrote: > From: Borislav Petkov <bp@suse.de> > > And add the first control option > > umip=warnings_off > > which disables warnings resulting from emulating UMIP-enabled insns. > > The actual use case is for users playing games in wine, games like > Overwatch, for example, which go nuts with SIDT: > > [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. > > filling up the kernel log unnecessarily with the same info over and over > again which doesn't mean a whit to the users - they just wanna play. > > So add a boot-time control switch for those warning messages. > > Reported-by: Marcus Rückert <mrueckert@suse.com> > Signed-off-by: Borislav Petkov <bp@suse.de> > --- > .../admin-guide/kernel-parameters.txt | 5 +++ > arch/x86/kernel/umip.c | 33 +++++++++++++++++-- > 2 files changed, 35 insertions(+), 3 deletions(-) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index 828d11441ebf..815d022c3e87 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -5887,6 +5887,11 @@ > unknown_nmi_panic > [X86] Cause panic on unknown NMI. > > + umip=warnings_off > + [X86] > + * warnings_off - do not issue warnings when emulating > + UMIP-enabled instructions. > + > usbcore.authorized_default= > [USB] Default USB device authorization: > (default -1 = authorized except for wireless USB, > diff --git a/arch/x86/kernel/umip.c b/arch/x86/kernel/umip.c > index 576b47e7523d..1d37dc626011 100644 > --- a/arch/x86/kernel/umip.c > +++ b/arch/x86/kernel/umip.c > @@ -90,10 +90,19 @@ static const char * const umip_insns[5] = { > [UMIP_INST_STR] = "STR", > }; > > -#define umip_pr_err(regs, fmt, ...) \ > +static struct umip_config { > + __u64 warnings_off : 1, > + __reserved : 63; > +} umip_cfg; > + > +#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_warn(regs, fmt, ...) \ > +({ \ > + if (!umip_cfg.warnings_off) \ > + umip_printk(regs, KERN_WARNING, fmt, ##__VA_ARGS__); \ > +}) > > /** > * umip_printk() - Print a rate-limited message > @@ -407,5 +416,23 @@ bool fixup_umip_exception(struct pt_regs *regs) > > /* increase IP to let the program keep going */ > regs->ip += insn.length; > +
Strictly, this hunk does not logically belong to this patch. I guess it is harmless, though. Admittedly, the new line should have been there since umip.c was added.
> return true; > } > + > +static int __init parse_umip_param(char *str) > +{ > + if (!str) > + return 0; > + > + if (*str == '=') > + str++; > + > + if (!strcmp(str, "warnings_off")) > + umip_cfg.warnings_off = 1; > + else > + return 0; > + > + return 1; > +} > +__setup("umip", parse_umip_param);
Wouldn't it be better to use parse_option_str() with __setup("umip=", parse_umip_param)? This would avoid the first two checks.
Thanks and BR, Ricardo
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