linux-kernel - Re: [PATCH] x86/mm/ptdump: display page encryption state

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Message-ID: <Yl+zdNP/5iHtPolv@kernel.org>
Date:   Wed, 20 Apr 2022 10:17:08 +0300
From:   Mike Rapoport <rppt@...nel.org>
To:     Dave Hansen <dave.hansen@...el.com>
Cc:     Borislav Petkov <bp@...en8.de>, Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/mm/ptdump: display page encryption state

On Tue, Apr 19, 2022 at 11:57:47AM -0700, Dave Hansen wrote:
> On 4/19/22 07:35, Mike Rapoport wrote:
> > When memory encryption is enabled, for instance in SEV guest, it is useful
> > to see what memory ranges are mapped as encrypted in the kernel page tables
> > and what ranges are left plain.
> > 
> > Add printing of 'ENC' for the encrypted ranges to the page table dumps.
> > 
> > Signed-off-by: Mike Rapoport <rppt@...ux.ibm.com>
> > ---
> >  arch/x86/mm/dump_pagetables.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
> > index e1b599ecbbc2..187dd17b8780 100644
> > --- a/arch/x86/mm/dump_pagetables.c
> > +++ b/arch/x86/mm/dump_pagetables.c
> > @@ -201,6 +201,10 @@ static void printk_prot(struct seq_file *m, pgprotval_t pr, int level, bool dmsg
> >  			pt_dump_cont_printf(m, dmsg, "PCD ");
> >  		else
> >  			pt_dump_cont_printf(m, dmsg, "    ");
> > +		if (pr & _PAGE_ENC)
> > +			pt_dump_cont_printf(m, dmsg, "ENC ");
> > +		else
> > +			pt_dump_cont_printf(m, dmsg, "    ");
> 
> _PAGE_ENC is AMD-specific.  Could we do this with a new generic "cc_"
> function, maybe cc_is_enc()?
> 
> Something like this would (I think) work for both SEV and TDX:
> 
> bool cc_is_enc(u64 prot)
> {
> 	return cc_mkdec(prot) != prot;
> }

It works for SEV. I can repost with this and you'll confirm it works on
TDX?

-- 
Sincerely yours,
Mike.