From: Dexuan Cui <decui@microsoft.com>
To: Dave Hansen <dave.hansen@intel.com>,
"Michael Kelley (LINUX)" <mikelley@microsoft.com>,
"ak@linux.intel.com" <ak@linux.intel.com>,
"arnd@arndb.de" <arnd@arndb.de>, "bp@alien8.de" <bp@alien8.de>,
"brijesh.singh@amd.com" <brijesh.singh@amd.com>,
"Williams, Dan J" <dan.j.williams@intel.com>,
"dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
"hpa@zytor.com" <hpa@zytor.com>,
"jane.chu@oracle.com" <jane.chu@oracle.com>,
"kirill.shutemov@linux.intel.com"
<kirill.shutemov@linux.intel.com>,
KY Srinivasan <kys@microsoft.com>,
"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
"linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
"luto@kernel.org" <luto@kernel.org>,
"mingo@redhat.com" <mingo@redhat.com>,
"peterz@infradead.org" <peterz@infradead.org>,
"rostedt@goodmis.org" <rostedt@goodmis.org>,
"sathyanarayanan.kuppuswamy@linux.intel.com"
<sathyanarayanan.kuppuswamy@linux.intel.com>,
"seanjc@google.com" <seanjc@google.com>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"tony.luck@intel.com" <tony.luck@intel.com>,
"wei.liu@kernel.org" <wei.liu@kernel.org>,
"x86@kernel.org" <x86@kernel.org>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH 5/6] x86/hyperv: Support hypercalls for TDX guests
Date: Mon, 28 Nov 2022 20:36:37 +0000 [thread overview]
Message-ID: <SA1PR21MB1335BA75F51964636745E486BF139@SA1PR21MB1335.namprd21.prod.outlook.com> (raw)
In-Reply-To: <f6d27366-e083-b362-b44c-eaf4d3365b53@intel.com>
> From: Dave Hansen <dave.hansen@intel.com>
> Sent: Monday, November 28, 2022 11:48 AM
>
> On 11/28/22 11:37, Dexuan Cui wrote:
> >> From: Dave Hansen <dave.hansen@intel.com>
> ...
> >> How do we know, for instance, that no hypercall using this interface
> >> will *ever* take the 0x0 physical address as an argument?
> >
> > A 0x0 physical address as an argument still works: the 0 is passed
> > to the hypervisor using GHCI. I believe Hyper-V interprets the 0 as
> > an error (if the param is needed), and returns an "invalid parameter"
> > error code to the guest.
>
> I don't see any data in the public documentation to support the claim
> that 0x0 is a special argument for either the input or output GPA
> parameters.
Sorry, I didn't make it clear. I meant: for some hypercalls, Hyper-V
doesn't really need an "input" param or an "output" param, so Linux
passes 0 for such a "not needed" param. Maybe Linux can pass any
value for such a "not needed" param, if Hyper-V just ignores the
"not needed" param. Some examples:
arch/x86/hyperv/hv_init.c: hv_get_partition_id():
status = hv_do_hypercall(HVCALL_GET_PARTITION_ID, NULL, output_page);
drivers/pci/controller/pci-hyperv.c:
res = hv_do_hypercall(HVCALL_RETARGET_INTERRUPT | (var_size << 17),
params, NULL);
If a param is needed and is supposed to be a non-zero memory address,
Linux running as a TDX guest must pass "cc_mkdec(address)" rather than
"address", otherwise I suspect the result is undefined, e.g. Hyper-V might
return an error to the guest, or Hyper-V might just terminate the guest,
especially if Linux passes 0 or cc_mkdec(0).
Currently all the users of hv_do_hypercall() pass valid arguments.
> This is despite some actual discussion on things like their alignment
> requirements[1] and interactions with overlay pages.
>
> So, either you are mistaken about that behavior, or it looks like the
> documentation needs updating.
The above is just my conjecture. I don't know how exactly Hyper-V works.
next prev parent reply other threads:[~2022-11-28 20:36 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-21 19:51 [PATCH 0/6] Support TDX guests on Hyper-V Dexuan Cui
2022-11-21 19:51 ` [PATCH 1/6] x86/tdx: Support hypercalls for " Dexuan Cui
2022-11-21 20:38 ` Dave Hansen
2022-11-21 23:52 ` Kirill A. Shutemov
2022-11-23 1:37 ` Dexuan Cui
2022-11-23 1:56 ` Dexuan Cui
2022-11-23 16:04 ` Dave Hansen
2022-11-23 18:59 ` Dexuan Cui
2022-11-23 3:52 ` Sathyanarayanan Kuppuswamy
2022-11-23 14:40 ` Kirill A. Shutemov
2022-11-23 18:55 ` Dexuan Cui
2022-11-30 19:14 ` Dexuan Cui
2022-12-02 21:47 ` 'Kirill A. Shutemov'
2022-11-23 16:03 ` Dave Hansen
2022-11-21 19:51 ` [PATCH 2/6] x86/tdx: Retry TDVMCALL_MAP_GPA() when needed Dexuan Cui
2022-11-21 20:55 ` Dave Hansen
2022-11-23 2:55 ` Dexuan Cui
2022-11-22 0:01 ` Kirill A. Shutemov
2022-11-23 3:27 ` Dexuan Cui
2022-11-23 13:30 ` Michael Kelley (LINUX)
2022-11-28 0:07 ` Dexuan Cui
2022-11-21 19:51 ` [PATCH 3/6] x86/tdx: Support vmalloc() for tdx_enc_status_changed() Dexuan Cui
2022-11-21 21:00 ` Dave Hansen
2022-11-23 4:01 ` Dexuan Cui
2022-11-22 0:24 ` Kirill A. Shutemov
2022-11-23 23:51 ` Dexuan Cui
2022-11-24 7:51 ` Kirill A. Shutemov
2022-11-27 20:27 ` Dexuan Cui
2022-11-21 19:51 ` [PATCH 4/6] x86/hyperv: Add hv_isolation_type_tdx() to detect TDX guests Dexuan Cui
2022-11-21 21:01 ` Dave Hansen
2022-11-21 21:48 ` Borislav Petkov
2022-11-22 0:32 ` Sathyanarayanan Kuppuswamy
2022-11-23 19:13 ` Dexuan Cui
2022-11-21 19:51 ` [PATCH 5/6] x86/hyperv: Support hypercalls for " Dexuan Cui
2022-11-21 20:05 ` Dave Hansen
2022-11-23 2:14 ` Dexuan Cui
2022-11-23 14:47 ` Kirill A. Shutemov
2022-11-23 18:13 ` Dexuan Cui
2022-11-23 18:18 ` Sathyanarayanan Kuppuswamy
2022-11-23 19:07 ` Dexuan Cui
2022-11-23 14:45 ` Michael Kelley (LINUX)
2022-11-28 0:58 ` Dexuan Cui
2022-11-28 1:20 ` Michael Kelley (LINUX)
2022-11-28 1:36 ` Dexuan Cui
2022-11-28 1:21 ` Sathyanarayanan Kuppuswamy
2022-11-28 1:55 ` Dexuan Cui
2022-11-28 15:22 ` Dave Hansen
2022-11-28 19:03 ` Dexuan Cui
2022-11-28 19:11 ` Dave Hansen
2022-11-28 19:37 ` Dexuan Cui
2022-11-28 19:48 ` Dave Hansen
2022-11-28 20:36 ` Dexuan Cui [this message]
2022-11-28 21:15 ` Dave Hansen
2022-11-28 21:53 ` Dexuan Cui
2022-11-21 19:51 ` [PATCH 6/6] Drivers: hv: vmbus: Support " Dexuan Cui
2023-01-06 11:00 ` Zhi Wang
2023-01-09 6:59 ` Dexuan Cui
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=SA1PR21MB1335BA75F51964636745E486BF139@SA1PR21MB1335.namprd21.prod.outlook.com \
--to=decui@microsoft.com \
--cc=ak@linux.intel.com \
--cc=arnd@arndb.de \
--cc=bp@alien8.de \
--cc=brijesh.singh@amd.com \
--cc=dan.j.williams@intel.com \
--cc=dave.hansen@intel.com \
--cc=dave.hansen@linux.intel.com \
--cc=haiyangz@microsoft.com \
--cc=hpa@zytor.com \
--cc=jane.chu@oracle.com \
--cc=kirill.shutemov@linux.intel.com \
--cc=kys@microsoft.com \
--cc=linux-arch@vger.kernel.org \
--cc=linux-hyperv@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@kernel.org \
--cc=mikelley@microsoft.com \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=rostedt@goodmis.org \
--cc=sathyanarayanan.kuppuswamy@linux.intel.com \
--cc=seanjc@google.com \
--cc=tglx@linutronix.de \
--cc=tony.luck@intel.com \
--cc=wei.liu@kernel.org \
--cc=x86@kernel.org \
/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).