From: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>
To: Borislav Petkov <bp@alien8.de>
Cc: linux-hyperv@vger.kernel.org, stefan.bader@canonical.com,
tim.gardner@canonical.com, roxana.nicolescu@canonical.com,
cascardo@canonical.com, kys@microsoft.com,
haiyangz@microsoft.com, wei.liu@kernel.org, sashal@kernel.org,
stable@vger.kernel.org, linux-kernel@vger.kernel.org,
"H. Peter Anvin" <hpa@zytor.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Ingo Molnar <mingo@redhat.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Michael Kelley <mhkelley58@gmail.com>,
Nikolay Borisov <nik.borisov@suse.com>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Tom Lendacky <thomas.lendacky@amd.com>,
x86@kernel.org, Dexuan Cui <decui@microsoft.com>
Subject: Re: [PATCH v1 1/3] x86/tdx: Check for TDX partitioning during early TDX init
Date: Mon, 4 Dec 2023 20:37:36 +0100 [thread overview]
Message-ID: <e11b0d18-2f58-4ddd-8f17-309e1a999b61@linux.microsoft.com> (raw)
In-Reply-To: <20231129164049.GVZWdpkVlc8nUvl/jx@fat_crate.local>
On 29/11/2023 17:40, Borislav Petkov wrote:
> On Wed, Nov 22, 2023 at 06:19:20PM +0100, Jeremi Piotrowski wrote:
>> Which approach do you prefer?
>
> I'm trying to figure out from the whole thread, what this guest is.
Wanted to clarify some things directly here. This type guest is supported
in the kernel already[1], so this whole series is the kind of attempt to
share more code that you advocated for in another email.
[1]: https://lore.kernel.org/lkml/20230824080712.30327-1-decui@microsoft.com/#t
>
> * A HyperV second-level guest
From Hyper-V's point of view it's a TDX guest with privilege levels inside, not
second-level...
>
> * of type TDX
...but Intel TDX calls these privilege levels L1 and L2 instead of VMPL0/VMPL1-3.
>
> * Needs to defer cc_mask and page visibility bla...
>
The implementations in tdx_early_init() depend on TDX module calls (not avail)
and the correct calls are standard Hyper-V hypercalls (same as vTOM SNP guests).
> * needs to disable TDX module calls
>
> * stub out tdx_accept_memory
This is actually a fix that for something that only works by accident right now
and I meant to post separately from the rest of the discussion.
If you look at arch/x86/include/asm/unaccepted_memory.h (below), it is used by both
CONFIG_INTEL_TDX_GUEST and CONFIG_AMD_MEM_ENCRYPT, but there is no tdx_accept_memory
implementation when CONFIG_INTEL_TDX_GUEST is not set. This is subtle and confusing,
the stub should be there.
static inline void arch_accept_memory(phys_addr_t start, phys_addr_t end)
{
/* Platform-specific memory-acceptance call goes here */
if (cpu_feature_enabled(X86_FEATURE_TDX_GUEST)) {
if (!tdx_accept_memory(start, end))
panic("TDX: Failed to accept memory\n");
} else if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) {
snp_accept_memory(start, end);
} else {
panic("Cannot accept memory: unknown platform\n");
}
}
>
> Anything else?
>
> And my worry is that this is going to become a mess and your patches
> already show that it is going in that direction because you need to run
> the TDX side but still have *some* things done differently. Which is
> needed because this is a different type of guest, even if it is a TDX
> one.
>
> Which reminds me, we have amd_cc_platform_vtom() which is a similar type
> of thing.
>
> And the TDX side could do something similar and at least *try* to
> abstract away all that stuff.
>
> Would it be nice? Of course not!
>
> How can one model a virt zoo of at least a dozen guest types but still
> keep code sane... :-\
>
next prev parent reply other threads:[~2023-12-04 19:37 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-22 17:01 [PATCH v1 1/3] x86/tdx: Check for TDX partitioning during early TDX init Jeremi Piotrowski
2023-11-22 17:01 ` [PATCH v1 2/3] x86/coco: Disable TDX module calls when TD partitioning is active Jeremi Piotrowski
2023-11-23 14:13 ` Kirill A. Shutemov
2023-11-24 10:38 ` Jeremi Piotrowski
2023-11-29 10:37 ` Huang, Kai
2023-12-01 15:27 ` Jeremi Piotrowski
2023-11-22 17:01 ` [PATCH v1 3/3] x86/tdx: Provide stub tdx_accept_memory() for non-TDX configs Jeremi Piotrowski
2023-11-23 14:11 ` Kirill A. Shutemov
2023-11-24 10:00 ` Jeremi Piotrowski
2023-11-22 17:19 ` [PATCH v1 1/3] x86/tdx: Check for TDX partitioning during early TDX init Jeremi Piotrowski
2023-11-29 16:40 ` Borislav Petkov
2023-11-30 7:08 ` Reshetova, Elena
2023-11-30 7:55 ` Borislav Petkov
2023-11-30 8:31 ` Reshetova, Elena
2023-11-30 9:21 ` Borislav Petkov
2023-12-04 16:44 ` Jeremi Piotrowski
2023-12-04 13:39 ` Jeremi Piotrowski
2023-12-04 19:37 ` Jeremi Piotrowski [this message]
2023-11-23 13:58 ` Kirill A. Shutemov
2023-11-24 10:31 ` Jeremi Piotrowski
2023-11-24 10:43 ` Kirill A. Shutemov
2023-11-24 11:04 ` Jeremi Piotrowski
2023-11-24 13:33 ` Kirill A. Shutemov
2023-11-24 16:19 ` Jeremi Piotrowski
2023-11-29 4:36 ` Huang, Kai
2023-12-01 16:16 ` Jeremi Piotrowski
2023-12-05 13:26 ` Huang, Kai
2023-12-06 18:47 ` Jeremi Piotrowski
2023-12-07 12:58 ` Huang, Kai
2023-12-07 17:21 ` Jeremi Piotrowski
2023-12-07 19:35 ` Jeremi Piotrowski
2023-12-08 10:51 ` Huang, Kai
2023-12-07 17:36 ` Reshetova, Elena
2023-12-08 12:45 ` Jeremi Piotrowski
2023-12-04 9:17 ` Reshetova, Elena
2023-12-04 19:07 ` Jeremi Piotrowski
2023-12-05 10:54 ` Kirill A. Shutemov
2023-12-06 17:49 ` Jeremi Piotrowski
2023-12-06 22:54 ` Kirill A. Shutemov
2023-12-07 17:06 ` Jeremi Piotrowski
2023-12-07 20:56 ` Kirill A. Shutemov
2023-12-05 13:24 ` Reshetova, Elena
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