From: Tom Lendacky <thomas.lendacky@amd.com>
To: Michael Kelley <mikelley@microsoft.com>,
hpa@zytor.com, kys@microsoft.com, haiyangz@microsoft.com,
wei.liu@kernel.org, decui@microsoft.com, luto@kernel.org,
peterz@infradead.org, davem@davemloft.net, edumazet@google.com,
kuba@kernel.org, pabeni@redhat.com, lpieralisi@kernel.org,
robh@kernel.org, kw@linux.com, bhelgaas@google.com,
arnd@arndb.de, hch@infradead.org, m.szyprowski@samsung.com,
robin.murphy@arm.com, brijesh.singh@amd.com, tglx@linutronix.de,
mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com,
Tianyu.Lan@microsoft.com, kirill.shutemov@linux.intel.com,
sathyanarayanan.kuppuswamy@linux.intel.com, ak@linux.intel.com,
isaku.yamahata@intel.com, dan.j.williams@intel.com,
jane.chu@oracle.com, seanjc@google.com, tony.luck@intel.com,
x86@kernel.org, linux-kernel@vger.kernel.org,
linux-hyperv@vger.kernel.org, netdev@vger.kernel.org,
linux-pci@vger.kernel.org, linux-arch@vger.kernel.org,
iommu@lists.linux.dev
Subject: Re: [Patch v3 05/14] x86/mm: Handle decryption/re-encryption of bss_decrypted consistently
Date: Wed, 16 Nov 2022 15:15:56 -0600 [thread overview]
Message-ID: <8c9554a7-7569-ec5b-8da4-6f169d3fefda@amd.com> (raw)
In-Reply-To: <4d27540e-691e-bd86-0f70-1faff39f7187@amd.com>
On 11/16/22 14:35, Tom Lendacky wrote:
> On 11/16/22 12:41, Michael Kelley wrote:
>> Current code in sme_postprocess_startup() decrypts the bss_decrypted
>> section when sme_me_mask is non-zero. But code in
>> mem_encrypt_free_decrytped_mem() re-encrypts the unused portion based
>> on CC_ATTR_MEM_ENCRYPT. In a Hyper-V guest VM using vTOM, these
>> conditions are not equivalent as sme_me_mask is always zero when
>> using vTOM. Consequently, mem_encrypt_free_decrypted_mem() attempts
>> to re-encrypt memory that was never decrypted.
>>
>> Fix this in mem_encrypt_free_decrypted_mem() by conditioning the
>> re-encryption on the same test for non-zero sme_me_mask. Hyper-V
>> guests using vTOM don't need the bss_decrypted section to be
>> decrypted, so skipping the decryption/re-encryption doesn't cause
>> a problem.
>>
>> Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Meant to add this in the previous reply...
With the change to use sme_me_mask directly
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
>> ---
>> arch/x86/mm/mem_encrypt_amd.c | 10 +++++++---
>> 1 file changed, 7 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/x86/mm/mem_encrypt_amd.c b/arch/x86/mm/mem_encrypt_amd.c
>> index 9c4d8db..5a51343 100644
>> --- a/arch/x86/mm/mem_encrypt_amd.c
>> +++ b/arch/x86/mm/mem_encrypt_amd.c
>> @@ -513,10 +513,14 @@ void __init mem_encrypt_free_decrypted_mem(void)
>> npages = (vaddr_end - vaddr) >> PAGE_SHIFT;
>> /*
>> - * The unused memory range was mapped decrypted, change the encryption
>> - * attribute from decrypted to encrypted before freeing it.
>> + * If the unused memory range was mapped decrypted, change the
>> encryption
>> + * attribute from decrypted to encrypted before freeing it. Base the
>> + * re-encryption on the same condition used for the decryption in
>> + * sme_postprocess_startup(). Higher level abstractions, such as
>> + * CC_ATTR_MEM_ENCRYPT, aren't necessarily equivalent in a Hyper-V VM
>> + * using vTOM, where sme_me_mask is always zero.
>> */
>> - if (cc_platform_has(CC_ATTR_MEM_ENCRYPT)) {
>> + if (sme_get_me_mask()) {
>
> To be consistent within this file, you should use sme_me_mask directly.
>
> Thanks,
> Tom
>
>> r = set_memory_encrypted(vaddr, npages);
>> if (r) {
>> pr_warn("failed to free unused decrypted pages\n");
next prev parent reply other threads:[~2022-11-16 21:16 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 [this message]
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)
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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