From: Dov Murik <dovmurik@linux.ibm.com>
To: Tom Lendacky <thomas.lendacky@amd.com>,
Zhi Wang <zhi.wang.linux@gmail.com>,
Michael Roth <michael.roth@amd.com>
Cc: kvm@vger.kernel.org, linux-coco@lists.linux.dev,
linux-mm@kvack.org, linux-crypto@vger.kernel.org, x86@kernel.org,
linux-kernel@vger.kernel.org, tglx@linutronix.de,
mingo@redhat.com, jroedel@suse.de, hpa@zytor.com,
ardb@kernel.org, pbonzini@redhat.com, seanjc@google.com,
vkuznets@redhat.com, jmattson@google.com, luto@kernel.org,
dave.hansen@linux.intel.com, slp@redhat.com, pgonda@google.com,
peterz@infradead.org, srinivas.pandruvada@linux.intel.com,
rientjes@google.com, tobin@ibm.com, bp@alien8.de, vbabka@suse.cz,
kirill@shutemov.name, ak@linux.intel.com, tony.luck@intel.com,
marcorr@google.com, sathyanarayanan.kuppuswamy@linux.intel.com,
alpergun@google.com, dgilbert@redhat.com, jarkko@kernel.org,
ashish.kalra@amd.com, nikunj.dadhania@amd.com,
Brijesh Singh <brijesh.singh@amd.com>,
Dov Murik <dovmurik@linux.ibm.com>
Subject: Re: [PATCH RFC v8 52/56] ccp: Add support to decrypt the page
Date: Thu, 2 Mar 2023 23:11:13 +0200 [thread overview]
Message-ID: <740d3ee7-e981-0812-f21e-296a7f350388@linux.ibm.com> (raw)
In-Reply-To: <36734887-6474-b43e-51ae-34f37e6670a5@amd.com>
On 02/03/2023 16:33, Tom Lendacky wrote:
> On 3/1/23 23:59, Dov Murik wrote:
>> Hi Mike, Zhi,
>>
>> On 01/03/2023 23:20, Zhi Wang wrote:
>>> On Mon, 20 Feb 2023 12:38:43 -0600
>>> Michael Roth <michael.roth@amd.com> wrote:
>>>
>>>> From: Brijesh Singh <brijesh.singh@amd.com>
>>>>
>>>> Add support to decrypt guest encrypted memory. These API interfaces can
>>>> be used for example to dump VMCBs on SNP guest exit.
>>>>
>>>
>>> What kinds of check will be applied from firmware when VMM decrypts this
>>> page? I suppose there has to be kinda mechanism to prevent VMM to
>>> decrypt
>>> any page in the guest. It would be nice to have some introduction about
>>> it in the comments.
>>>
>>
>> The SNP ABI spec says (section 8.27.2 SNP_DBG_DECRYPT):
>>
>> The firmware checks that the guest's policy allows debugging. If not,
>> the firmware returns POLICY_FAILURE.
>>
>> and in the Guest Policy (section 4.3):
>>
>> Bit 19 - DEBUG
>> 0: Debugging is disallowed.
>> 1: Debugging is allowed.
>>
>> In the kernel, that firmware error code is defined as
>> SEV_RET_POLICY_FAILURE.
>>
>>
>>>> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
>>>> Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
>>>> [mdr: minor commit fixups]
>>>> Signed-off-by: Michael Roth <michael.roth@amd.com>
>>>> ---
>>>> drivers/crypto/ccp/sev-dev.c | 32 ++++++++++++++++++++++++++++++++
>>>> include/linux/psp-sev.h | 22 ++++++++++++++++++++--
>>>> 2 files changed, 52 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/drivers/crypto/ccp/sev-dev.c
>>>> b/drivers/crypto/ccp/sev-dev.c
>>>> index e65563bc8298..bf5167b2acfc 100644
>>>> --- a/drivers/crypto/ccp/sev-dev.c
>>>> +++ b/drivers/crypto/ccp/sev-dev.c
>>>> @@ -2017,6 +2017,38 @@ int sev_guest_df_flush(int *error)
>>>> }
>>>> EXPORT_SYMBOL_GPL(sev_guest_df_flush);
>>>> +int snp_guest_dbg_decrypt_page(u64 gctx_pfn, u64 src_pfn, u64
>>>> dst_pfn, int *error)
>>>> +{
>>>> + struct sev_data_snp_dbg data = {0};
>>>> + struct sev_device *sev;
>>>> + int ret;
>>>> +
>>>> + if (!psp_master || !psp_master->sev_data)
>>>> + return -ENODEV;
>>>> +
>>>> + sev = psp_master->sev_data;
>>>> +
>>>> + if (!sev->snp_initialized)
>>>> + return -EINVAL;
>>>> +
>>>> + data.gctx_paddr = sme_me_mask | (gctx_pfn << PAGE_SHIFT);
>>>> + data.src_addr = sme_me_mask | (src_pfn << PAGE_SHIFT);
>>>> + data.dst_addr = sme_me_mask | (dst_pfn << PAGE_SHIFT);
>>
>> I guess this works, but I wonder why we need to turn on sme_me_mask on
>> teh dst_addr. I thought that the firmware decrypts the guest page
>> (src_addr) to a plaintext page. Couldn't find this requirement in the
>> SNP spec.
>
> This sme_me_mask tells the firmware how to access the host memory
> (similar to how DMA uses sme_me_mask when supplying addresses to devices
> under SME). This needs to match the pagetable mapping being used by the
> host, otherwise the contents will appears as ciphertext to the host if
> they are not in sync. Since the default pagetable mapping is encrypted,
> the sme_me_mask bit must be provided on the destination address. So it
> is not a spec requirement, but an SME implementation requirement.
>
Ah, OK, that's clear now. Thanks Tom.
-Dov
next prev parent reply other threads:[~2023-03-02 21:12 UTC|newest]
Thread overview: 147+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-20 18:37 [PATCH RFC v8 00/56] Add AMD Secure Nested Paging (SEV-SNP) Hypervisor Support Michael Roth
2023-02-20 18:37 ` [PATCH RFC v8 01/56] KVM: x86: Add 'fault_is_private' x86 op Michael Roth
2023-03-01 10:25 ` Zhi Wang
2023-03-18 4:51 ` Isaku Yamahata
2023-03-20 17:46 ` Michael Roth
2023-03-18 4:53 ` Isaku Yamahata
2023-02-20 18:37 ` [PATCH RFC v8 02/56] KVM: x86: Add 'update_mem_attr' " Michael Roth
2023-03-18 4:56 ` Isaku Yamahata
2023-03-20 18:05 ` Michael Roth
2023-03-21 11:21 ` Zhi Wang
2023-03-22 1:58 ` Michael Roth
2023-03-23 18:17 ` Zhi Wang
2023-03-28 4:36 ` Michael Roth
2023-03-28 23:00 ` Zhi Wang
2023-03-29 23:50 ` Michael Roth
2023-02-20 18:37 ` [PATCH RFC v8 03/56] KVM: x86: Add platform hooks for private memory invalidations Michael Roth
2023-03-18 5:13 ` Isaku Yamahata
2023-03-20 18:09 ` Michael Roth
2023-02-20 18:37 ` [PATCH RFC v8 04/56] KVM: Add HVA range operator Michael Roth
2023-02-20 21:37 ` Zhi Wang
2023-03-27 0:34 ` Michael Roth
2023-04-04 14:40 ` Zhi Wang
2023-02-20 18:37 ` [PATCH RFC v8 05/56] KVM: SEV: Require KVM_PROTECTED_VM when AMD_MEM_ENCRYPT is enabled Michael Roth
2023-02-20 18:37 ` [PATCH RFC v8 06/56] KVM: Split out memory attribute xarray updates to helper function Michael Roth
2023-02-20 18:37 ` [PATCH RFC v8 07/56] KVM: SEV: Populate private memory fd during LAUNCH_UPDATE_DATA Michael Roth
2023-02-20 18:37 ` [PATCH RFC v8 08/56] KVM: SEV: Rename sev_{pin,unpin}_memory Michael Roth
2023-03-03 14:00 ` Vlastimil Babka
2023-03-06 11:01 ` Nikunj A. Dadhania
2023-02-20 18:38 ` [PATCH RFC v8 09/56] KVM: SEV: Handle memory backed by restricted memfd Michael Roth
2023-03-03 14:05 ` Vlastimil Babka
2023-03-06 11:03 ` Nikunj A. Dadhania
2023-02-20 18:38 ` [PATCH RFC v8 10/56] x86/cpufeatures: Add SEV-SNP CPU feature Michael Roth
2023-02-21 21:21 ` Sathyanarayanan Kuppuswamy
2023-02-22 23:27 ` Kalra, Ashish
2023-02-20 18:38 ` [PATCH RFC v8 11/56] x86/sev: Add the host SEV-SNP initialization support Michael Roth
2023-02-20 20:12 ` Zhi Wang
2023-02-20 18:38 ` [PATCH RFC v8 12/56] x86/sev: Add RMP entry lookup helpers Michael Roth
2023-03-03 15:28 ` Vlastimil Babka
2023-03-29 22:59 ` Michael Roth
2023-04-20 16:31 ` Vlastimil Babka
2023-02-20 18:38 ` [PATCH RFC v8 13/56] x86/fault: Add helper for dumping RMP entries Michael Roth
2023-02-20 18:38 ` [PATCH RFC v8 14/56] x86/sev: Add helper functions for RMPUPDATE and PSMASH instruction Michael Roth
2023-02-20 18:38 ` [PATCH RFC v8 15/56] x86/sev: Invalidate pages from the direct map when adding them to the RMP table Michael Roth
2023-03-01 12:07 ` Tom Dohrmann
2023-03-01 16:15 ` Dave Hansen
2023-03-28 22:12 ` Michael Roth
2023-02-20 18:38 ` [PATCH RFC v8 16/56] x86/traps: Define RMP violation #PF error code Michael Roth
2023-02-20 18:38 ` [PATCH RFC v8 17/56] x86/fault: Add support to handle the RMP fault for user address Michael Roth
2023-03-01 16:21 ` Dave Hansen
2023-03-28 23:31 ` Michael Roth
2023-04-11 18:27 ` Dave Hansen
2023-03-03 15:31 ` Vlastimil Babka
2023-02-20 18:38 ` [PATCH RFC v8 18/56] x86/fault: fix handle_split_page_fault() to work with memfd backed pages Michael Roth
2023-02-20 19:57 ` Hugh Dickins
2023-02-20 20:31 ` Michael Roth
2023-02-20 18:38 ` [PATCH RFC v8 19/56] x86/fault: Return pfn from dump_pagetable() for SEV-specific fault handling Michael Roth
2023-02-20 21:13 ` Zhi Wang
2023-02-28 10:53 ` Wu Zongyong
2023-02-20 18:38 ` [PATCH RFC v8 20/56] crypto:ccp: Define the SEV-SNP commands Michael Roth
2023-04-17 14:54 ` Sabin Rapan
2023-02-20 18:38 ` [PATCH RFC v8 21/56] crypto: ccp: Add support to initialize the AMD-SP for SEV-SNP Michael Roth
2023-02-20 18:38 ` [PATCH RFC v8 22/56] crypto:ccp: Provide API to issue SEV and SNP commands Michael Roth
2023-02-20 18:38 ` [PATCH RFC v8 23/56] crypto: ccp: Introduce snp leaked pages list Michael Roth
2023-03-03 15:54 ` Vlastimil Babka
2023-02-20 18:38 ` [PATCH RFC v8 24/56] crypto: ccp: Handle the legacy TMR allocation when SNP is enabled Michael Roth
2023-02-21 9:28 ` Zhi Wang
2023-02-21 15:31 ` Kalra, Ashish
2023-02-21 21:15 ` Zhi Wang
2023-02-21 22:06 ` Kalra, Ashish
2023-02-20 18:38 ` [PATCH RFC v8 25/56] crypto: ccp: Handle the legacy SEV command " Michael Roth
2023-02-20 18:38 ` [PATCH RFC v8 26/56] crypto: ccp: Add the SNP_PLATFORM_STATUS command Michael Roth
2023-02-20 18:38 ` [PATCH RFC v8 27/56] crypto: ccp: Add the SNP_{SET,GET}_EXT_CONFIG command Michael Roth
2023-02-22 12:32 ` Zhi Wang
2023-02-22 16:50 ` Tom Lendacky
2023-02-22 22:43 ` Kalra, Ashish
2023-02-23 6:38 ` Zhi Wang
2023-02-23 14:19 ` Tom Lendacky
2023-02-20 18:38 ` [PATCH RFC v8 28/56] crypto: ccp: Provide APIs to query extended attestation report Michael Roth
2023-02-22 20:24 ` Zhi Wang
2023-02-22 22:35 ` Kalra, Ashish
2023-02-23 8:14 ` Zhi Wang
2023-02-20 18:38 ` [PATCH RFC v8 29/56] KVM: SVM: Add support to handle AP reset MSR protocol Michael Roth
2023-02-20 18:38 ` [PATCH RFC v8 30/56] KVM: SVM: Provide the Hypervisor Feature support VMGEXIT Michael Roth
2023-02-20 18:38 ` [PATCH RFC v8 31/56] KVM: SVM: Make AVIC backing, VMSA and VMCB memory allocation SNP safe Michael Roth
2023-02-22 20:42 ` Zhi Wang
2023-02-20 18:38 ` [PATCH RFC v8 32/56] KVM: SVM: Add initial SEV-SNP support Michael Roth
2023-02-23 17:46 ` Zhi Wang
2023-02-20 18:38 ` [PATCH RFC v8 33/56] KVM: SVM: Add KVM_SNP_INIT command Michael Roth
2023-02-20 18:38 ` [PATCH RFC v8 34/56] KVM: SVM: Add KVM_SEV_SNP_LAUNCH_START command Michael Roth
2023-02-23 21:41 ` Zhi Wang
2023-02-24 16:22 ` Tom Lendacky
2023-04-26 17:06 ` Sabin Rapan
2023-04-26 18:02 ` Tom Lendacky
2023-02-20 18:38 ` [PATCH RFC v8 35/56] KVM: SVM: Add KVM_SEV_SNP_LAUNCH_UPDATE command Michael Roth
2023-02-24 11:55 ` Zhi Wang
2023-02-20 18:38 ` [PATCH RFC v8 36/56] KVM: SVM: Add KVM_SEV_SNP_LAUNCH_FINISH command Michael Roth
2023-03-24 14:40 ` Alexander Graf
2023-02-20 18:38 ` [PATCH RFC v8 37/56] KVM: X86: Keep the NPT and RMP page level in sync Michael Roth
2023-02-20 18:38 ` [PATCH RFC v8 38/56] KVM: x86: Define RMP page fault error bits for #NPF Michael Roth
2023-02-20 18:38 ` [PATCH RFC v8 39/56] KVM: SVM: Add support to handle GHCB GPA register VMGEXIT Michael Roth
2023-02-20 18:38 ` [PATCH RFC v8 40/56] KVM: SVM: Add KVM_EXIT_VMGEXIT Michael Roth
2023-02-20 18:38 ` [PATCH RFC v8 41/56] KVM: SVM: Add support to handle MSR based Page State Change VMGEXIT Michael Roth
2023-02-24 15:06 ` Zhi Wang
2023-02-20 18:38 ` [PATCH RFC v8 42/56] KVM: SVM: Add support to handle " Michael Roth
2023-02-20 18:38 ` [PATCH RFC v8 43/56] KVM: x86: Export the kvm_zap_gfn_range() for the SNP use Michael Roth
2023-02-20 18:38 ` [PATCH RFC v8 44/56] KVM: SVM: Add support to handle the RMP nested page fault Michael Roth
2023-02-28 19:11 ` Zhi Wang
2023-02-20 18:38 ` [PATCH RFC v8 45/56] KVM: SVM: Provide support for SNP_GUEST_REQUEST NAE event Michael Roth
2023-02-24 11:01 ` Alexander Graf
2023-02-28 19:34 ` Zhi Wang
2023-04-17 13:05 ` Alexander Graf
2023-02-20 18:38 ` [PATCH RFC v8 46/56] KVM: SVM: Use a VMSA physical address variable for populating VMCB Michael Roth
2023-02-20 18:38 ` [PATCH RFC v8 47/56] KVM: SVM: Support SEV-SNP AP Creation NAE event Michael Roth
2023-02-24 12:37 ` Alexander Graf
2023-02-28 20:47 ` Zhi Wang
2023-03-01 21:14 ` Alexander Graf
2023-04-05 0:54 ` Michael Roth
2023-04-04 22:48 ` Michael Roth
2023-04-05 15:20 ` Tom Lendacky
2023-02-20 18:38 ` [PATCH RFC v8 48/56] KVM: SVM: Add SNP-specific handling for memory attribute updates Michael Roth
2023-03-01 23:37 ` Dave Hansen
2023-04-05 23:48 ` Michael Roth
2023-02-20 18:38 ` [PATCH RFC v8 49/56] KVM: SVM: Implement .fault_is_private callback for SNP Michael Roth
2023-02-20 18:38 ` [PATCH RFC v8 50/56] KVM: SEV: Handle restricted memory invalidations " Michael Roth
2023-03-01 10:41 ` Zhi Wang
2023-02-20 18:38 ` [PATCH RFC v8 51/56] KVM: SVM: Add module parameter to enable the SEV-SNP Michael Roth
2023-03-01 10:45 ` Zhi Wang
2023-02-20 18:38 ` [PATCH RFC v8 52/56] ccp: Add support to decrypt the page Michael Roth
2023-03-01 21:20 ` Zhi Wang
2023-03-02 5:59 ` Dov Murik
2023-03-02 14:33 ` Tom Lendacky
2023-03-02 21:11 ` Dov Murik [this message]
2023-02-20 18:38 ` [PATCH RFC v8 53/56] KVM: SVM: Make VMSAVE target area memory allocation SNP safe Michael Roth
2023-03-01 21:23 ` Zhi Wang
2023-02-20 18:38 ` [PATCH RFC v8 54/56] x86/sev: Add KVM commands for instance certs Michael Roth
2023-02-21 12:40 ` Dov Murik
2023-03-02 0:02 ` Zhi Wang
2023-03-02 1:41 ` Dionna Amalie Glaze
2023-03-02 11:27 ` Zhi Wang
2023-03-02 11:34 ` Dov Murik
2023-02-20 18:38 ` [PATCH RFC v8 55/56] x86/sev: Document KVM_SEV_SNP_{G,S}ET_CERTS Michael Roth
2023-02-20 18:38 ` [PATCH RFC v8 56/56] iommu/amd: Add IOMMU_SNP_SHUTDOWN support Michael Roth
2023-03-01 16:56 ` [PATCH RFC v8 00/56] Add AMD Secure Nested Paging (SEV-SNP) Hypervisor Support Dave Hansen
2023-03-01 22:59 ` Zhi Wang
2023-03-01 23:39 ` Dave Hansen
2023-08-03 18:27 ` Schander, Johanna 'Mimoja' Amelie
2023-08-04 1:01 ` Kalra, Ashish
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