From: Borislav Petkov <bp@alien8.de>
To: Michael Kelley <mikelley@microsoft.com>
Cc: 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@lst.de, m.szyprowski@samsung.com,
robin.murphy@arm.com, thomas.lendacky@amd.com,
brijesh.singh@amd.com, tglx@linutronix.de, mingo@redhat.com,
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 v6 06/13] x86/hyperv: Change vTOM handling to use standard coco mechanisms
Date: Mon, 20 Mar 2023 12:22:58 +0100 [thread overview]
Message-ID: <20230320112258.GCZBhCEpNAIk0rUDnx@fat_crate.local> (raw)
In-Reply-To: <1678329614-3482-7-git-send-email-mikelley@microsoft.com>
On Wed, Mar 08, 2023 at 06:40:07PM -0800, Michael Kelley wrote:
> diff --git a/arch/x86/coco/core.c b/arch/x86/coco/core.c
> index 49b44f8..d1c3306 100644
> --- a/arch/x86/coco/core.c
> +++ b/arch/x86/coco/core.c
> @@ -88,8 +106,6 @@ bool cc_platform_has(enum cc_attr attr)
> return amd_cc_platform_has(attr);
> case CC_VENDOR_INTEL:
> return intel_cc_platform_has(attr);
> - case CC_VENDOR_HYPERV:
> - return hyperv_cc_platform_has(attr);
> default:
> return false;
> }
> @@ -103,11 +119,14 @@ u64 cc_mkenc(u64 val)
> * encryption status of the page.
> *
> * - for AMD, bit *set* means the page is encrypted
> - * - for Intel *clear* means encrypted.
> + * - for AMD with vTOM and for Intel, *clear* means encrypted
> */
> switch (vendor) {
> case CC_VENDOR_AMD:
> - return val | cc_mask;
> + if (sev_status & MSR_AMD64_SNP_VTOM)
> + return val & ~cc_mask;
This is silly. It should simply be:
if (sev_status & MSR_AMD64_SNP_VTOM)
return val;
> + else
> + return val | cc_mask;
> case CC_VENDOR_INTEL:
> return val & ~cc_mask;
> default:
> @@ -120,7 +139,10 @@ u64 cc_mkdec(u64 val)
> /* See comment in cc_mkenc() */
> switch (vendor) {
> case CC_VENDOR_AMD:
> - return val & ~cc_mask;
> + if (sev_status & MSR_AMD64_SNP_VTOM)
> + return val | cc_mask;
So if you set the C-bit, that doesn't make it decrypted on AMD. cc_mask
on VTOM is 0 so why even bother?
Same as the above.
> + else
> + return val & ~cc_mask;
> case CC_VENDOR_INTEL:
> return val | cc_mask;
> default:
...
> +void __init hv_vtom_init(void)
> +{
> + /*
> + * By design, a VM using vTOM doesn't see the SEV setting,
> + * so SEV initialization is bypassed and sev_status isn't set.
> + * Set it here to indicate a vTOM VM.
> + */
This looks like a hack. The SEV status MSR cannot be intercepted so the
guest should see vTOM. How are you running vTOM without setting it even up?!
> + sev_status = MSR_AMD64_SNP_VTOM;
> + cc_set_vendor(CC_VENDOR_AMD);
> + cc_set_mask(ms_hyperv.shared_gpa_boundary);
> + physical_mask &= ms_hyperv.shared_gpa_boundary - 1;
> +
> + x86_platform.hyper.is_private_mmio = hv_is_private_mmio;
> + x86_platform.guest.enc_cache_flush_required = hv_vtom_cache_flush_required;
> + x86_platform.guest.enc_tlb_flush_required = hv_vtom_tlb_flush_required;
> + x86_platform.guest.enc_status_change_finish = hv_vtom_set_host_visibility;
> +}
> +
> +#endif /* CONFIG_AMD_MEM_ENCRYPT */
> +
> /*
> * hv_map_memory - map memory to extra space in the AMD SEV-SNP Isolation VM.
> */
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2023-03-20 11:23 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-09 2:40 [PATCH v6 00/13] Add PCI pass-thru support to Hyper-V Confidential VMs Michael Kelley
2023-03-09 2:40 ` [PATCH v6 01/13] x86/ioremap: Add hypervisor callback for private MMIO mapping in coco VM Michael Kelley
2023-03-27 20:09 ` [tip: x86/sev] " tip-bot2 for Michael Kelley
2023-03-09 2:40 ` [PATCH v6 02/13] x86/hyperv: Reorder code to facilitate future work Michael Kelley
2023-03-09 2:40 ` [PATCH v6 03/13] Drivers: hv: Explicitly request decrypted in vmap_pfn() calls Michael Kelley
2023-03-09 2:40 ` [PATCH v6 04/13] x86/mm: Handle decryption/re-encryption of bss_decrypted consistently Michael Kelley
2023-03-27 20:09 ` [tip: x86/sev] " tip-bot2 for Michael Kelley
2023-03-09 2:40 ` [PATCH v6 05/13] init: Call mem_encrypt_init() after Hyper-V hypercall init is done Michael Kelley
2023-03-27 20:09 ` [tip: x86/sev] " tip-bot2 for Michael Kelley
2023-03-09 2:40 ` [PATCH v6 06/13] x86/hyperv: Change vTOM handling to use standard coco mechanisms Michael Kelley
2023-03-20 11:22 ` Borislav Petkov [this message]
2023-03-20 13:30 ` Michael Kelley (LINUX)
2023-03-20 18:16 ` Borislav Petkov
2023-03-20 18:50 ` Michael Kelley (LINUX)
2023-03-23 13:43 ` Borislav Petkov
2023-03-24 15:48 ` Borislav Petkov
2023-03-24 17:10 ` Dexuan Cui
2023-03-24 17:28 ` Sathyanarayanan Kuppuswamy
2023-03-24 18:30 ` Borislav Petkov
2023-03-24 19:36 ` Michael Kelley (LINUX)
2023-03-25 0:04 ` Michael Kelley (LINUX)
2023-03-09 2:40 ` [PATCH v6 07/13] swiotlb: Remove bounce buffer remapping for Hyper-V Michael Kelley
2023-03-09 2:40 ` [PATCH v6 08/13] Drivers: hv: vmbus: Remove second mapping of VMBus monitor pages Michael Kelley
2023-03-09 2:40 ` [PATCH v6 09/13] Drivers: hv: vmbus: Remove second way of mapping ring buffers Michael Kelley
2023-03-09 2:40 ` [PATCH v6 10/13] hv_netvsc: Remove second mapping of send and recv buffers Michael Kelley
2023-03-09 2:40 ` [PATCH v6 11/13] Drivers: hv: Don't remap addresses that are above shared_gpa_boundary Michael Kelley
2023-03-09 2:40 ` [PATCH v6 12/13] PCI: hv: Add hypercalls to read/write MMIO space Michael Kelley
2023-03-24 14:48 ` Lorenzo Pieralisi
2023-03-24 15:13 ` Michael Kelley (LINUX)
2023-03-24 15:24 ` Lorenzo Pieralisi
2023-03-09 2:40 ` [PATCH v6 13/13] PCI: hv: Enable PCI pass-thru devices in Confidential VMs Michael Kelley
2023-03-20 11:27 ` [PATCH v6 00/13] Add PCI pass-thru support to Hyper-V " Borislav Petkov
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