linux-kernel - Re: [PATCHv2 22/29] x86/tdx: Make pages shared in ioremap()

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <f1dfc268-7b2f-9980-27ce-0b5bb1aea962@amd.com>
Date:   Tue, 15 Feb 2022 08:49:34 -0600
From:   Tom Lendacky <thomas.lendacky@....com>
To:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Borislav Petkov <bp@...en8.de>
Cc:     Dave Hansen <dave.hansen@...el.com>, tglx@...utronix.de,
        mingo@...hat.com, luto@...nel.org, peterz@...radead.org,
        sathyanarayanan.kuppuswamy@...ux.intel.com, aarcange@...hat.com,
        ak@...ux.intel.com, dan.j.williams@...el.com, david@...hat.com,
        hpa@...or.com, jgross@...e.com, jmattson@...gle.com,
        joro@...tes.org, jpoimboe@...hat.com, knsathya@...nel.org,
        pbonzini@...hat.com, sdeep@...are.com, seanjc@...gle.com,
        tony.luck@...el.com, vkuznets@...hat.com, wanpengli@...cent.com,
        x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCHv2 22/29] x86/tdx: Make pages shared in ioremap()

On 2/14/22 16:09, Kirill A. Shutemov wrote:
> On Mon, Feb 07, 2022 at 06:28:04PM +0100, Borislav Petkov wrote:
>> On Mon, Feb 07, 2022 at 08:57:39AM -0800, Dave Hansen wrote:
>>> We can surely *do* this with cc_something() helpers.  It's just not as
>>> easy as making cc_set/cc_clear().
>>
>> Sure, that's easy: cc_pgprot_{enc,dec}() or so.
> 
> So, I've ended up with this in <asm/pgtable.h>
> 
> /*
>   * Macros to add or remove encryption attribute
>   */
> #ifdef CONFIG_ARCH_HAS_CC_PLATFORM
> pgprotval_t cc_enc(pgprotval_t protval);
> pgprotval_t cc_dec(pgprotval_t protval);
> #define pgprot_encrypted(prot)	__pgprot(cc_enc(pgprot_val(prot)))
> #define pgprot_decrypted(prot)	__pgprot(cc_dec(pgprot_val(prot)))
> #else
> #define pgprot_encrypted(prot) (prot)
> #define pgprot_decrypted(prot) (prot)
> #endif

A couple of things. I think cc_pgprot_enc() and cc_pgprot_dec() would be 
more descriptive/better names to use here.

Also, can they be defined in include/linux/cc_platform.h (with two 
versions based on CONFIG_ARCH_HAS_CC_PLATFORM) and have that included 
here? Or is there some header file include issues when trying to include 
it? That would clean this block up into just two lines.

Thanks,
Tom

> 
> And cc_platform.c:
> 
> pgprotval_t cc_enc(pgprotval_t protval)
> {
> 	if (sme_me_mask)
> 		return __sme_set(protval);
> 	else if (cpu_feature_enabled(X86_FEATURE_TDX_GUEST))
> 		return protval & ~tdx_shared_mask();
> 	else
> 		return protval;
> }
> 
> pgprotval_t cc_dec(pgprotval_t protval)
> {
> 	if (sme_me_mask)
> 		return __sme_clr(protval);
> 	else if (cpu_feature_enabled(X86_FEATURE_TDX_GUEST))
> 		return protval | tdx_shared_mask();
> 	else
> 		return protval;
> }
> EXPORT_SYMBOL_GPL(cc_dec);