linux-kernel - RE: [PATCH] x86/mm: Print the encryption features correctly when a paravisor is present

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: <SA1PR21MB13352433C4D72AE19F1FF56EBFDBA@SA1PR21MB1335.namprd21.prod.outlook.com>
Date:   Fri, 20 Oct 2023 06:01:53 +0000
From:   Dexuan Cui <decui@...rosoft.com>
To:     Dave Hansen <dave.hansen@...el.com>,
        KY Srinivasan <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        "wei.liu@...nel.org" <wei.liu@...nel.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "bp@...en8.de" <bp@...en8.de>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "x86@...nel.org" <x86@...nel.org>, "hpa@...or.com" <hpa@...or.com>,
        "luto@...nel.org" <luto@...nel.org>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "stefan.bader@...onical.com" <stefan.bader@...onical.com>,
        Tim Gardner <tim.gardner@...onical.com>,
        "roxana.nicolescu@...onical.com" <roxana.nicolescu@...onical.com>,
        "cascardo@...onical.com" <cascardo@...onical.com>,
        "Michael Kelley (LINUX)" <mikelley@...rosoft.com>,
        "jgross@...e.com" <jgross@...e.com>,
        "sathyanarayanan.kuppuswamy@...ux.intel.com" 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        "kirill.shutemov@...ux.intel.com" <kirill.shutemov@...ux.intel.com>,
        "sashal@...nel.org" <sashal@...nel.org>,
        "matija.glavinic-pecotic.ext@...ia.com" 
        <matija.glavinic-pecotic.ext@...ia.com>,
        "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] x86/mm: Print the encryption features correctly when a
 paravisor is present

> From: Dave Hansen <dave.hansen@...el.com>
> Sent: Thursday, October 19, 2023 8:54 AM
> To: Dexuan Cui <decui@...rosoft.com>; KY Srinivasan
> [...]
> > --- a/arch/x86/hyperv/ivm.c
> > +++ b/arch/x86/hyperv/ivm.c
> > @@ -450,6 +450,16 @@ static bool hv_is_private_mmio(u64 addr)
> >  	return false;
> >  }
> >
> > +static void hv_print_mem_enc_feature_info(void)
> > +{
> > +	enum hv_isolation_type type = hv_get_isolation_type();
> > +
> > +	if (type == HV_ISOLATION_TYPE_SNP)
> > +		pr_info("Memory Encryption Features active: AMD
> SEV\n");
> > +	else if (type == HV_ISOLATION_TYPE_TDX)
> > +		pr_info("Memory Encryption Features active: Intel
> > TDX\n");
> > +}
> 
> If we draw this to its logical conclusion, every paravisor will need a
> pr_info() for every hardware CoCo implementation.  That M*N pr_info()s.
> That seems nuts.

This patch only modifies x86 related files. I think it's unlikely to see
a third hardware Coco implementation for x86 in the foreseeable feature (?)
When we have a third implementation, I suppose more code, e.g., the existing
print_mem_encrypt_feature_info(),  will have to be changed as well.

Currently it looks like there is only 1 paravisor implementation. 
I think we'll know if some code can be shared only when a second paravisor
implementation appears.

I can use the below version if you think it's better:

static const char *hv_mem_enc_features[] = {
        [ HV_ISOLATION_TYPE_SNP ] = "AMD SEV",
        [ HV_ISOLATION_TYPE_TDX ] = "Intel TDX",
};

static void hv_print_mem_enc_feature_info(void)
{
        enum hv_isolation_type type = hv_get_isolation_type();

        if (type < HV_ISOLATION_TYPE_SNP || type > HV_ISOLATION_TYPE_TDX)
                return;

        pr_info("Memory Encryption Features active:: %s\n",
                hv_mem_enc_features[type]);
}

Thanks,
Dexuan