linux-kernel - Re: [PATCH v3 24/75] x86/boot/compressed/64: Unmap GHCB page before booting the kernel

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Message-ID: <20200513113011.GG18353@8bytes.org>
Date:   Wed, 13 May 2020 13:30:11 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     Borislav Petkov <bp@...en8.de>
Cc:     x86@...nel.org, hpa@...or.com, Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Hellstrom <thellstrom@...are.com>,
        Jiri Slaby <jslaby@...e.cz>,
        Dan Williams <dan.j.williams@...el.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Juergen Gross <jgross@...e.com>,
        Kees Cook <keescook@...omium.org>,
        David Rientjes <rientjes@...gle.com>,
        Cfir Cohen <cfir@...gle.com>,
        Erdem Aktas <erdemaktas@...gle.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Mike Stunes <mstunes@...are.com>,
        Joerg Roedel <jroedel@...e.de>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH v3 24/75] x86/boot/compressed/64: Unmap GHCB page before
 booting the kernel

On Wed, May 13, 2020 at 01:13:40PM +0200, Borislav Petkov wrote:
> On Tue, Apr 28, 2020 at 05:16:34PM +0200, Joerg Roedel wrote:
> > @@ -302,9 +313,13 @@ void do_boot_page_fault(struct pt_regs *regs, unsigned long error_code)
> >  	 *	- User faults
> >  	 *	- Reserved bits set
> >  	 */
> > -	if (error_code & (X86_PF_PROT | X86_PF_USER | X86_PF_RSVD)) {
> > +	if (ghcb_fault ||
> > +	    error_code & (X86_PF_PROT | X86_PF_USER | X86_PF_RSVD)) {
> >  		/* Print some information for debugging */
> > -		error_putstr("Unexpected page-fault:");
> > +		if (ghcb_fault)
> > +			error_putstr("Page-fault on GHCB page:");
> > +		else
> > +			error_putstr("Unexpected page-fault:");
> 
> You could carve out the info dumping into a separate function to
> unclutter this if-statement (diff ontop):

Yeah, I had this this way in v2, but changed it upon you request[1] :)


	Joerg

[1] https://lore.kernel.org/lkml/20200402114941.GA9352@zn.tnic/