From: "Michael Kelley (LINUX)" <mikelley@microsoft.com>
To: Sathyanarayanan Kuppuswamy
<sathyanarayanan.kuppuswamy@linux.intel.com>,
Borislav Petkov <bp@alien8.de>
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Subject: RE: [Patch v3 05/14] x86/mm: Handle decryption/re-encryption of bss_decrypted consistently
Date: Tue, 22 Nov 2022 17:59:04 +0000 [thread overview]
Message-ID: <BYAPR21MB168873879B0EEF71DED3D460D70D9@BYAPR21MB1688.namprd21.prod.outlook.com> (raw)
In-Reply-To: <6b5129cf-6986-bbb1-7e60-37849fc383fc@linux.intel.com>
From: Sathyanarayanan Kuppuswamy <sathyanarayanan.kuppuswamy@linux.intel.com>
>
> On 11/21/22 6:39 AM, Borislav Petkov wrote:
> > On Fri, Nov 18, 2022 at 02:55:32AM +0000, Michael Kelley (LINUX) wrote:
> >> But I had not thought about TDX. In the TDX case, it appears that
> >> sme_postprocess_startup() will not decrypt the bss_decrypted section.
> >> The corresponding mem_encrypt_free_decrypted_mem() is a no-op unless
> >> CONFIG_AMD_MEM_ENCRYPT is set. But maybe if someone builds a
> >> kernel image that supports both TDX and AMD encryption, it could break
> >
> > sme_me_mask better be 0 on a kernel with both built in and running as a
> > TDX guest.
> >
>
> Yes. It will be 0 in TDX. In sme_enable(), AMD code checks for CPUID
> support before updating the sme_me_mask.
>
Right. But here's my point: With current code and an image built with
CONFIG_AMD_MEM_ENCRYPT=y and running as a TDX guest,
sme_postprocess_startup() will not decrypt the bss_decrypted section.
Then later mem_encrypt_free_decrypted_mem() will run, see that
CC_ATTR_MEM_ENCRYPT is true, and try to re-encrypt the memory.
In other words, a TDX guest would break in the same way as a Hyper-V
vTOM guest would break. This patch fixes the problem for both cases.
The only things I see in the bss_decrypted section are two clock structures
In arch/x86/kernel/kvmclock.c, which aren't needed when Hyper-V is the
hypervisor. But with a TDX guest on KVM, will *not* decrypting the
bss_decrypted section be a problem? I don't know that kvmclock
code or why the two clock structures need to be decrypted for
AMD mem encryption.
Michael
next prev parent reply other threads:[~2022-11-22 17:59 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-16 18:41 [Patch v3 00/14] Add PCI pass-thru support to Hyper-V Confidential VMs Michael Kelley
2022-11-16 18:41 ` [Patch v3 01/14] x86/ioremap: Fix page aligned size calculation in __ioremap_caller() Michael Kelley
2022-11-21 13:32 ` Borislav Petkov
2022-11-21 16:40 ` Michael Kelley (LINUX)
2022-11-21 19:45 ` Borislav Petkov
2022-11-21 21:02 ` Michael Kelley (LINUX)
2022-11-21 18:14 ` Dave Hansen
2022-11-21 21:04 ` Michael Kelley (LINUX)
2022-11-21 21:08 ` Borislav Petkov
2022-11-16 18:41 ` [Patch v3 02/14] x86/ioapic: Gate decrypted mapping on cc_platform_has() attribute Michael Kelley
2022-11-17 21:39 ` Sathyanarayanan Kuppuswamy
2022-11-21 13:50 ` Borislav Petkov
2022-11-21 16:43 ` Michael Kelley (LINUX)
2022-11-21 19:47 ` Borislav Petkov
2022-11-16 18:41 ` [Patch v3 03/14] x86/hyperv: Reorder code in prep for subsequent patch Michael Kelley
2022-11-16 18:41 ` [Patch v3 04/14] Drivers: hv: Explicitly request decrypted in vmap_pfn() calls Michael Kelley
2022-11-16 18:41 ` [Patch v3 05/14] x86/mm: Handle decryption/re-encryption of bss_decrypted consistently Michael Kelley
2022-11-16 20:35 ` Tom Lendacky
2022-11-16 21:15 ` Tom Lendacky
2022-11-18 2:59 ` Michael Kelley (LINUX)
2022-11-17 21:47 ` Sathyanarayanan Kuppuswamy
2022-11-18 2:55 ` Michael Kelley (LINUX)
2022-11-21 14:39 ` Borislav Petkov
2022-11-21 22:06 ` Sathyanarayanan Kuppuswamy
2022-11-22 17:59 ` Michael Kelley (LINUX) [this message]
2022-11-28 10:50 ` Borislav Petkov
2022-11-28 2:52 ` Dexuan Cui
2022-11-28 14:15 ` Tom Lendacky
2022-11-28 18:06 ` Dexuan Cui
2022-11-21 14:40 ` Borislav Petkov
2022-11-16 18:41 ` [Patch v3 06/14] init: Call mem_encrypt_init() after Hyper-V hypercall init is done Michael Kelley
2022-11-16 21:14 ` Tom Lendacky
2022-11-21 14:46 ` Borislav Petkov
2022-11-16 18:41 ` [Patch v3 07/14] x86/hyperv: Change vTOM handling to use standard coco mechanisms Michael Kelley
2022-11-17 2:59 ` Tianyu Lan
2022-11-21 15:03 ` Borislav Petkov
2022-11-22 18:22 ` Michael Kelley (LINUX)
2022-11-22 18:30 ` Dave Hansen
2022-11-22 22:02 ` Michael Kelley (LINUX)
2022-11-22 22:18 ` Borislav Petkov
2022-11-23 0:59 ` Michael Kelley (LINUX)
2022-11-28 14:38 ` Michael Kelley (LINUX)
2022-11-28 16:33 ` Borislav Petkov
2022-11-28 16:59 ` Michael Kelley (LINUX)
2022-11-28 17:24 ` Borislav Petkov
2022-11-28 17:55 ` Michael Kelley (LINUX)
2022-11-28 19:56 ` Borislav Petkov
2022-11-29 1:15 ` Michael Kelley (LINUX)
2022-11-29 8:40 ` Borislav Petkov
2022-11-29 15:49 ` Michael Kelley (LINUX)
2022-11-29 17:47 ` Borislav Petkov
2022-11-30 16:11 ` Michael Kelley (LINUX)
2022-11-16 18:41 ` [Patch v3 08/14] swiotlb: Remove bounce buffer remapping for Hyper-V Michael Kelley
2022-11-16 18:41 ` [Patch v3 09/14] Drivers: hv: vmbus: Remove second mapping of VMBus monitor pages Michael Kelley
2022-11-16 18:41 ` [Patch v3 10/14] Drivers: hv: vmbus: Remove second way of mapping ring buffers Michael Kelley
2022-11-16 18:41 ` [Patch v3 11/14] hv_netvsc: Remove second mapping of send and recv buffers Michael Kelley
2022-11-16 18:41 ` [Patch v3 12/14] Drivers: hv: Don't remap addresses that are above shared_gpa_boundary Michael Kelley
2022-11-16 18:41 ` [Patch v3 13/14] PCI: hv: Add hypercalls to read/write MMIO space Michael Kelley
2022-11-17 15:16 ` Wei Liu
2022-11-17 16:14 ` Michael Kelley (LINUX)
2022-11-17 17:01 ` Wei Liu
2022-11-17 16:32 ` Sean Christopherson
2022-11-17 17:00 ` Wei Liu
2022-11-17 18:33 ` Haiyang Zhang
2022-11-18 2:38 ` Michael Kelley (LINUX)
2022-11-16 18:41 ` [Patch v3 14/14] PCI: hv: Enable PCI pass-thru devices in Confidential VMs Michael Kelley
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