From: "Huang, Kai" <kai.huang@intel.com>
To: "Hansen, Dave" <dave.hansen@intel.com>,
"isaku.yamahata@gmail.com" <isaku.yamahata@gmail.com>
Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"Luck, Tony" <tony.luck@intel.com>,
"david@redhat.com" <david@redhat.com>,
"bagasdotme@gmail.com" <bagasdotme@gmail.com>,
"ak@linux.intel.com" <ak@linux.intel.com>,
"Wysocki, Rafael J" <rafael.j.wysocki@intel.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Chatre, Reinette" <reinette.chatre@intel.com>, "Christopherson,,
Sean" <seanjc@google.com>,
"pbonzini@redhat.com" <pbonzini@redhat.com>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"kirill.shutemov@linux.intel.com"
<kirill.shutemov@linux.intel.com>,
"Yamahata, Isaku" <isaku.yamahata@intel.com>,
"Shahar, Sagi" <sagis@google.com>,
"peterz@infradead.org" <peterz@infradead.org>,
"imammedo@redhat.com" <imammedo@redhat.com>,
"Gao, Chao" <chao.gao@intel.com>,
"Brown, Len" <len.brown@intel.com>,
"sathyanarayanan.kuppuswamy@linux.intel.com"
<sathyanarayanan.kuppuswamy@linux.intel.com>,
"Huang, Ying" <ying.huang@intel.com>,
"Williams, Dan J" <dan.j.williams@intel.com>
Subject: Re: [PATCH v10 05/16] x86/virt/tdx: Add skeleton to enable TDX on demand
Date: Thu, 23 Mar 2023 22:09:45 +0000 [thread overview]
Message-ID: <6be93d78e01906ff5c3714005170d761e5b40d41.camel@intel.com> (raw)
In-Reply-To: <141def31-dcbb-70ae-2935-4fb06a986036@intel.com>
On Thu, 2023-03-23 at 06:49 -0700, Hansen, Dave wrote:
> On 3/15/23 04:10, Huang, Kai wrote:
> > I can do. Just want to make sure do you want to retry TDX_SYS_BUSY, or retry
> > TDX_RND_NO_ENTROPY (if we want to ask TDX module guys to change to return this
> > value)?
>
> I'll put it this way:
>
> Linux is going to treat TDX_SYS_BUSY like a Linux bug and assume
> Linux is doing something wrong. It'll mostly mean that
> users will see something nasty and may even cause Linux to give
> up on TDX. In other words, the TDX module shouldn't use
> TDX_SYS_BUSY for things that aren't Linux's fault.
>
> > Also, even we retry either TDX_SYS_BUSY or TDX_RND_NO_ENTROPY in common
> > seamcall() code, it doesn't handle the TDH.SYS.KEY.CONFIG, because sadly this
> > SEAMCALL returns a different error code:
> >
> > TDX_KEY_GENERATION_FAILED Failed to generate a random key. This is
> > typically caused by an entropy error of the
> > CPU's random number generator, and may
> > be impacted by RDSEED, RDRAND or PCONFIG
> > executing on other LPs. The operation should be
> > retried.
>
> Sounds like we should just replace TDX_KEY_GENERATION_FAILED with
> TDX_RND_NO_ENTROPY in cases where key generation fails because of a lack
> of entropy.
Thanks for feedback.
I'll do following, please let me know for any comments in case I have any
misunderstanding.
1) In TDH.SYS.INIT, ask TDX module team to return TDX_RND_NO_ENTROPY instead of
TDX_SYS_BUSY when running out of entropy.
2) In TDH.SYS.KEY.CONFIG, ask TDX module to return TDX_RND_NO_ENTROPY instead of
TDX_KEY_GENERATION_FAILED when running out of entropy. Whether
TDX_KEY_GENERATION_FAILED should be still kept is up to TDX module team
(because it looks running concurrent PCONFIGs is also related).
3) Ask TDX module to always return TDX_RND_NO_ENTROPY in _ALL_ SEAMCALLs and
keep this behaviour for future TDX modules too.
4) In the common seamcall(), retry on TDX_RND_NO_ENTROPY.
In terms of how many times to retry, I will use a fixed value for now, similar
to the kernel code below:
#define RDRAND_RETRY_LOOPS 10
/* Unconditional execution of RDRAND and RDSEED */
static inline bool __must_check rdrand_long(unsigned long *v)
{
bool ok;
unsigned int retry = RDRAND_RETRY_LOOPS;
do {
asm volatile("rdrand %[out]"
CC_SET(c)
: CC_OUT(c) (ok), [out] "=r" (*v));
if (ok)
return true;
} while (--retry);
return false;
}
next prev parent reply other threads:[~2023-03-23 22:09 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-06 14:13 [PATCH v10 00/16] TDX host kernel support Kai Huang
2023-03-06 14:13 ` [PATCH v10 01/16] x86/tdx: Define TDX supported page sizes as macros Kai Huang
2023-03-16 12:37 ` David Hildenbrand
2023-03-16 22:41 ` Huang, Kai
2023-03-06 14:13 ` [PATCH v10 02/16] x86/virt/tdx: Detect TDX during kernel boot Kai Huang
2023-03-16 12:48 ` David Hildenbrand
2023-03-16 22:37 ` Huang, Kai
2023-03-23 17:02 ` David Hildenbrand
2023-03-23 22:15 ` Huang, Kai
2023-03-06 14:13 ` [PATCH v10 03/16] x86/virt/tdx: Make INTEL_TDX_HOST depend on X86_X2APIC Kai Huang
2023-03-16 12:57 ` David Hildenbrand
2023-03-06 14:13 ` [PATCH v10 04/16] x86/virt/tdx: Add SEAMCALL infrastructure Kai Huang
2023-03-06 14:13 ` [PATCH v10 05/16] x86/virt/tdx: Add skeleton to enable TDX on demand Kai Huang
2023-03-08 22:27 ` Isaku Yamahata
2023-03-12 23:08 ` Huang, Kai
2023-03-13 23:49 ` Isaku Yamahata
2023-03-14 1:50 ` Huang, Kai
2023-03-14 4:02 ` Isaku Yamahata
2023-03-14 5:45 ` Dave Hansen
2023-03-14 17:16 ` Isaku Yamahata
2023-03-14 17:38 ` Dave Hansen
2023-03-14 15:48 ` Dave Hansen
2023-03-15 11:10 ` Huang, Kai
2023-03-16 22:07 ` Huang, Kai
2023-03-23 13:49 ` Dave Hansen
2023-03-23 22:09 ` Huang, Kai [this message]
2023-03-23 22:12 ` Dave Hansen
2023-03-23 22:42 ` Huang, Kai
2023-03-16 0:31 ` Isaku Yamahata
2023-03-16 2:45 ` Isaku Yamahata
2023-03-16 2:52 ` Huang, Kai
2023-03-06 14:13 ` [PATCH v10 06/16] x86/virt/tdx: Get information about TDX module and TDX-capable memory Kai Huang
2023-03-06 14:13 ` [PATCH v10 07/16] x86/virt/tdx: Use all system memory when initializing TDX module as TDX memory Kai Huang
2023-03-09 1:38 ` Isaku Yamahata
2023-03-06 14:13 ` [PATCH v10 08/16] x86/virt/tdx: Add placeholder to construct TDMRs to cover all TDX memory regions Kai Huang
2023-03-06 14:13 ` [PATCH v10 09/16] x86/virt/tdx: Fill out " Kai Huang
2023-03-06 14:13 ` [PATCH v10 10/16] x86/virt/tdx: Allocate and set up PAMTs for TDMRs Kai Huang
2023-03-21 7:44 ` Dong, Eddie
2023-03-21 8:05 ` Huang, Kai
2023-03-06 14:13 ` [PATCH v10 11/16] x86/virt/tdx: Designate reserved areas for all TDMRs Kai Huang
2023-03-06 14:13 ` [PATCH v10 12/16] x86/virt/tdx: Configure TDX module with the TDMRs and global KeyID Kai Huang
2023-03-06 14:13 ` [PATCH v10 13/16] x86/virt/tdx: Configure global KeyID on all packages Kai Huang
2023-03-06 14:13 ` [PATCH v10 14/16] x86/virt/tdx: Initialize all TDMRs Kai Huang
2023-03-06 14:14 ` [PATCH v10 15/16] x86/virt/tdx: Flush cache in kexec() when TDX is enabled Kai Huang
2023-03-06 14:14 ` [PATCH v10 16/16] Documentation/x86: Add documentation for TDX host support Kai Huang
2023-03-08 1:11 ` [PATCH v10 00/16] TDX host kernel support Isaku Yamahata
2023-03-16 12:35 ` David Hildenbrand
2023-03-16 22:06 ` Huang, Kai
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=6be93d78e01906ff5c3714005170d761e5b40d41.camel@intel.com \
--to=kai.huang@intel.com \
--cc=ak@linux.intel.com \
--cc=bagasdotme@gmail.com \
--cc=chao.gao@intel.com \
--cc=dan.j.williams@intel.com \
--cc=dave.hansen@intel.com \
--cc=david@redhat.com \
--cc=imammedo@redhat.com \
--cc=isaku.yamahata@gmail.com \
--cc=isaku.yamahata@intel.com \
--cc=kirill.shutemov@linux.intel.com \
--cc=kvm@vger.kernel.org \
--cc=len.brown@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=pbonzini@redhat.com \
--cc=peterz@infradead.org \
--cc=rafael.j.wysocki@intel.com \
--cc=reinette.chatre@intel.com \
--cc=sagis@google.com \
--cc=sathyanarayanan.kuppuswamy@linux.intel.com \
--cc=seanjc@google.com \
--cc=tglx@linutronix.de \
--cc=tony.luck@intel.com \
--cc=ying.huang@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).