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From: Dave Hansen <dave.hansen@intel.com>
To: "Michael Kelley (LINUX)" <mikelley@microsoft.com>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	Sathyanarayanan Kuppuswamy 
	<sathyanarayanan.kuppuswamy@linux.intel.com>,
	"Kirill A. Shutemov" <kirill@shutemov.name>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	"tglx@linutronix.de" <tglx@linutronix.de>,
	"mingo@redhat.com" <mingo@redhat.com>,
	"bp@alien8.de" <bp@alien8.de>, Dexuan Cui <decui@microsoft.com>,
	"rick.p.edgecombe@intel.com" <rick.p.edgecombe@intel.com>,
	"seanjc@google.com" <seanjc@google.com>,
	"x86@kernel.org" <x86@kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"stable@vger.kernel.org" <stable@vger.kernel.org>
Subject: Re: [PATCHv2 2/3] x86/tdx: Fix race between set_memory_encrypted() and load_unaligned_zeropad()
Date: Fri, 2 Jun 2023 10:42:33 -0700	[thread overview]
Message-ID: <d73d41cc-0578-7bf3-46a2-b47eea44bdd0@intel.com> (raw)
In-Reply-To: <BYAPR21MB168826D6C870542E5BD3372BD74EA@BYAPR21MB1688.namprd21.prod.outlook.com>

On 6/2/23 09:11, Michael Kelley (LINUX) wrote:
> Tom -- Does the above sequence *depend* on the hypervisor doing anything
> to make it work?  I'm not clear on why KVM would automatically change the
> page over to private.  If there's a dependency on the hypervisor doing
> something, then it seems like we'll need to standardize that "something"
> across hypervisors, lest we end up with per-hypervisor code in Linux to handle
> this scenario.  And running SEV-SNP with multiple VMPLs probably makes it
> even more complicated.
> 
> Kirill -- Same question about TDX.  Does making load_unaligned_zeropad()
> work in a TDX VM depend on the hypervisor doing anything?  Or is the
> behavior seen by the guest dependent only on architected behavior of
> the TDX processor?

No, there's no active help from the hypervisor here.

Also, fwiw, the "architected behavior" here is really just the TDX
module policy and _arguably_ the hardware Secure-EPT controlled by the
TDX module.

  parent reply	other threads:[~2023-06-02 17:42 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-05-26 12:02 [PATCHv2 0/3] x86/tdx: Fix one more load_unaligned_zeropad() issue Kirill A. Shutemov
2023-05-26 12:02 ` [PATCHv2 1/3] x86/mm: Allow guest.enc_status_change_prepare() to fail Kirill A. Shutemov
2023-05-26 21:50   ` Sathyanarayanan Kuppuswamy
2023-05-26 12:02 ` [PATCHv2 2/3] x86/tdx: Fix race between set_memory_encrypted() and load_unaligned_zeropad() Kirill A. Shutemov
2023-05-26 22:10   ` Sathyanarayanan Kuppuswamy
2023-05-30  0:57     ` Kirill A. Shutemov
2023-05-30 12:57       ` Tom Lendacky
2023-05-30 13:22         ` Sathyanarayanan Kuppuswamy
     [not found]           ` <BYAPR21MB1688EF2A57E90FCE02B82F84D748A@BYAPR21MB1688.namprd21.prod.outlook.com>
2023-06-01 18:19             ` Tom Lendacky
2023-06-02 16:11               ` Michael Kelley (LINUX)
2023-06-02 17:05                 ` Tom Lendacky
2023-06-02 17:42                 ` Dave Hansen [this message]
2023-06-05 12:12                   ` Kirill A. Shutemov
2023-06-05 23:13   ` Dave Hansen
2023-05-26 12:02 ` [PATCHv2 3/3] x86/mm: Fix enc_status_change_finish_noop() Kirill A. Shutemov
2023-05-30 13:20   ` Sathyanarayanan Kuppuswamy

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