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0f4a1e80 |
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12-Mar-2024 |
Kevin Loughlin <kevinloughlin@google.com> |
x86/sev: Skip ROM range scans and validation for SEV-SNP guests SEV-SNP requires encrypted memory to be validated before access. Because the ROM memory range is not part of the e820 table, it is not pre-validated by the BIOS. Therefore, if a SEV-SNP guest kernel wishes to access this range, the guest must first validate the range. The current SEV-SNP code does indeed scan the ROM range during early boot and thus attempts to validate the ROM range in probe_roms(). However, this behavior is neither sufficient nor necessary for the following reasons: * With regards to sufficiency, if EFI_CONFIG_TABLES are not enabled and CONFIG_DMI_SCAN_MACHINE_NON_EFI_FALLBACK is set, the kernel will attempt to access the memory at SMBIOS_ENTRY_POINT_SCAN_START (which falls in the ROM range) prior to validation. For example, Project Oak Stage 0 provides a minimal guest firmware that currently meets these configuration conditions, meaning guests booting atop Oak Stage 0 firmware encounter a problematic call chain during dmi_setup() -> dmi_scan_machine() that results in a crash during boot if SEV-SNP is enabled. * With regards to necessity, SEV-SNP guests generally read garbage (which changes across boots) from the ROM range, meaning these scans are unnecessary. The guest reads garbage because the legacy ROM range is unencrypted data but is accessed via an encrypted PMD during early boot (where the PMD is marked as encrypted due to potentially mapping actually-encrypted data in other PMD-contained ranges). In one exceptional case, EISA probing treats the ROM range as unencrypted data, which is inconsistent with other probing. Continuing to allow SEV-SNP guests to use garbage and to inconsistently classify ROM range encryption status can trigger undesirable behavior. For instance, if garbage bytes appear to be a valid signature, memory may be unnecessarily reserved for the ROM range. Future code or other use cases may result in more problematic (arbitrary) behavior that should be avoided. While one solution would be to overhaul the early PMD mapping to always treat the ROM region of the PMD as unencrypted, SEV-SNP guests do not currently rely on data from the ROM region during early boot (and even if they did, they would be mostly relying on garbage data anyways). As a simpler solution, skip the ROM range scans (and the otherwise- necessary range validation) during SEV-SNP guest early boot. The potential SEV-SNP guest crash due to lack of ROM range validation is thus avoided by simply not accessing the ROM range. In most cases, skip the scans by overriding problematic x86_init functions during sme_early_init() to SNP-safe variants, which can be likened to x86_init overrides done for other platforms (ex: Xen); such overrides also avoid the spread of cc_platform_has() checks throughout the tree. In the exceptional EISA case, still use cc_platform_has() for the simplest change, given (1) checks for guest type (ex: Xen domain status) are already performed here, and (2) these checks occur in a subsys initcall instead of an x86_init function. [ bp: Massage commit message, remove "we"s. ] Fixes: 9704c07bf9f7 ("x86/kernel: Validate ROM memory before accessing when SEV-SNP is active") Signed-off-by: Kevin Loughlin <kevinloughlin@google.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Cc: <stable@kernel.org> Link: https://lore.kernel.org/r/20240313121546.2964854-1-kevinloughlin@google.com
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b82a8dbd |
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04-Dec-2023 |
Kirill A. Shutemov <kirill.shutemov@linux.intel.com> |
x86/coco: Disable 32-bit emulation by default on TDX and SEV The INT 0x80 instruction is used for 32-bit x86 Linux syscalls. The kernel expects to receive a software interrupt as a result of the INT 0x80 instruction. However, an external interrupt on the same vector triggers the same handler. The kernel interprets an external interrupt on vector 0x80 as a 32-bit system call that came from userspace. A VMM can inject external interrupts on any arbitrary vector at any time. This remains true even for TDX and SEV guests where the VMM is untrusted. Put together, this allows an untrusted VMM to trigger int80 syscall handling at any given point. The content of the guest register file at that moment defines what syscall is triggered and its arguments. It opens the guest OS to manipulation from the VMM side. Disable 32-bit emulation by default for TDX and SEV. User can override it with the ia32_emulation=y command line option. [ dhansen: reword the changelog ] Reported-by: Supraja Sridhara <supraja.sridhara@inf.ethz.ch> Reported-by: Benedict Schlüter <benedict.schlueter@inf.ethz.ch> Reported-by: Mark Kuhne <mark.kuhne@inf.ethz.ch> Reported-by: Andrin Bertschi <andrin.bertschi@inf.ethz.ch> Reported-by: Shweta Shinde <shweta.shinde@inf.ethz.ch> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Borislav Petkov (AMD) <bp@alien8.de> Cc: <stable@vger.kernel.org> # v6.0+: 1da5c9b x86: Introduce ia32_enabled() Cc: <stable@vger.kernel.org> # v6.0+
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d6f274b7 |
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10-Oct-2023 |
Alexander Shishkin <alexander.shishkin@linux.intel.com> |
x86/sev: Drop unneeded #include Commit: 20f07a044a76 ("x86/sev: Move common memory encryption code to mem_encrypt.c") ... forgot to remove the include of virtio_config.h from mem_encrypt_amd.c when it moved the related code to mem_encrypt.c (from where this include subsequently got removed by a later commit). Remove it now. Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com> Link: https://lore.kernel.org/r/20231010145220.3960055-3-alexander.shishkin@linux.intel.com
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6e74b125 |
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10-Oct-2023 |
Alexander Shishkin <alexander.shishkin@linux.intel.com> |
x86/sev: Move sev_setup_arch() to mem_encrypt.c Since commit: 4d96f9109109b ("x86/sev: Replace occurrences of sev_active() with cc_platform_has()") ... the SWIOTLB bounce buffer size adjustment and restricted virtio memory setting also inadvertently apply to TDX: the code is using cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) as a gatekeeping condition, which is also true for TDX, and this is also what we want. To reflect this, move the corresponding code to generic mem_encrypt.c. No functional changes intended. Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com> Link: https://lore.kernel.org/r/20231010145220.3960055-2-alexander.shishkin@linux.intel.com
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ac3f9c9f |
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24-Aug-2023 |
Steve Rutherford <srutherford@google.com> |
x86/sev: Make enc_dec_hypercall() accept a size instead of npages enc_dec_hypercall() accepted a page count instead of a size, which forced its callers to round up. As a result, non-page aligned vaddrs caused pages to be spuriously marked as decrypted via the encryption status hypercall, which in turn caused consistent corruption of pages during live migration. Live migration requires accurate encryption status information to avoid migrating pages from the wrong perspective. Fixes: 064ce6c550a0 ("mm: x86: Invoke hypercall when page encryption status is changed") Signed-off-by: Steve Rutherford <srutherford@google.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com> Reviewed-by: Pankaj Gupta <pankaj.gupta@amd.com> Tested-by: Ben Hillier <bhillier@google.com> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20230824223731.2055016-1-srutherford@google.com
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3f6819dd |
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05-Jun-2023 |
Kirill A. Shutemov <kirill.shutemov@linux.intel.com> |
x86/mm: Allow guest.enc_status_change_prepare() to fail TDX code is going to provide guest.enc_status_change_prepare() that is able to fail. TDX will use the call to convert the GPA range from shared to private. This operation can fail. Add a way to return an error from the callback. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> Link: https://lore.kernel.org/all/20230606095622.1939-2-kirill.shutemov%40linux.intel.com
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ff3cfcb0 |
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31-May-2023 |
Thomas Gleixner <tglx@linutronix.de> |
x86/smpboot: Fix the parallel bringup decision The decision to allow parallel bringup of secondary CPUs checks CC_ATTR_GUEST_STATE_ENCRYPT to detect encrypted guests. Those cannot use parallel bootup because accessing the local APIC is intercepted and raises a #VC or #VE, which cannot be handled at that point. The check works correctly, but only for AMD encrypted guests. TDX does not set that flag. As there is no real connection between CC attributes and the inability to support parallel bringup, replace this with a generic control flag in x86_cpuinit and let SEV-ES and TDX init code disable it. Fixes: 0c7ffa32dbd6 ("x86/smpboot/64: Implement arch_cpuhp_init_parallel_bringup() and enable it") Reported-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Tom Lendacky <thomas.lendacky@amd.com> Tested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Link: https://lore.kernel.org/r/87ilc9gd2d.ffs@tglx
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c7b5254b |
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08-Mar-2023 |
Michael Kelley <mikelley@microsoft.com> |
x86/mm: Handle decryption/re-encryption of bss_decrypted consistently sme_postprocess_startup() decrypts the bss_decrypted section when sme_me_mask is non-zero. mem_encrypt_free_decrypted_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. So check sme_me_mask in mem_encrypt_free_decrypted_mem() too. 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> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com> Link: https://lore.kernel.org/r/1678329614-3482-5-git-send-email-mikelley@microsoft.com
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4867fbbd |
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10-Jul-2022 |
Anshuman Khandual <anshuman.khandual@arm.com> |
x86/mm: move protection_map[] inside the platform This moves protection_map[] inside the platform and makes it a static. This also defines a helper function add_encrypt_protection_map() that can update the protection_map[] array with pgprot_encrypted(). Link: https://lkml.kernel.org/r/20220711070600.2378316-7-anshuman.khandual@arm.com Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Brian Cain <bcain@quicinc.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Christoph Hellwig <hch@infradead.org> Cc: Chris Zankel <chris@zankel.net> Cc: "David S. Miller" <davem@davemloft.net> Cc: Dinh Nguyen <dinguyen@kernel.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Guo Ren <guoren@kernel.org> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Huacai Chen <chenhuacai@kernel.org> Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com> Cc: Jeff Dike <jdike@addtoit.com> Cc: Jonas Bonn <jonas@southpole.se> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Simek <monstr@monstr.eu> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Richard Henderson <rth@twiddle.net> Cc: Rich Felker <dalias@libc.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Sam Ravnborg <sam@ravnborg.org> Cc: Stafford Horne <shorne@gmail.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Vineet Gupta <vgupta@kernel.org> Cc: WANG Xuerui <kernel@xen0n.name> Cc: Will Deacon <will@kernel.org> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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a603002e |
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22-Jun-2022 |
Juergen Gross <jgross@suse.com> |
virtio: replace restricted mem access flag with callback Instead of having a global flag to require restricted memory access for all virtio devices, introduce a callback which can select that requirement on a per-device basis. For convenience add a common function returning always true, which can be used for use cases like SEV. Per default use a callback always returning false. As the callback needs to be set in early init code already, add a virtio anchor which is builtin in case virtio is enabled. Signed-off-by: Juergen Gross <jgross@suse.com> Tested-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> # Arm64 guest using Xen Reviewed-by: Stefano Stabellini <sstabellini@kernel.org> Link: https://lore.kernel.org/r/20220622063838.8854-2-jgross@suse.com Signed-off-by: Juergen Gross <jgross@suse.com>
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3f9dfbeb |
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06-Jun-2022 |
Juergen Gross <jgross@suse.com> |
virtio: replace arch_has_restricted_virtio_memory_access() Instead of using arch_has_restricted_virtio_memory_access() together with CONFIG_ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS, replace those with platform_has() and a new platform feature PLATFORM_VIRTIO_RESTRICTED_MEM_ACCESS. Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> Tested-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> # Arm64 only Reviewed-by: Christoph Hellwig <hch@lst.de> Acked-by: Borislav Petkov <bp@suse.de>
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a3e23092 |
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29-Mar-2022 |
Christoph Hellwig <hch@lst.de> |
x86: centralize setting SWIOTLB_FORCE when guest memory encryption is enabled Move enabling SWIOTLB_FORCE for guest memory encryption into common code. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
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dc3f3d24 |
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24-Feb-2022 |
Brijesh Singh <brijesh.singh@amd.com> |
x86/mm: Validate memory when changing the C-bit Add the needed functionality to change pages state from shared to private and vice-versa using the Page State Change VMGEXIT as documented in the GHCB spec. Signed-off-by: Brijesh Singh <brijesh.singh@amd.com> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lore.kernel.org/r/20220307213356.2797205-22-brijesh.singh@amd.com
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5e5ccff6 |
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08-Feb-2022 |
Brijesh Singh <brijesh.singh@amd.com> |
x86/sev: Add helper for validating pages in early enc attribute changes early_set_memory_{encrypted,decrypted}() are used for changing the page state from decrypted (shared) to encrypted (private) and vice versa. When SEV-SNP is active, the page state transition needs to go through additional steps. If the page is transitioned from shared to private, then perform the following after the encryption attribute is set in the page table: 1. Issue the page state change VMGEXIT to add the page as a private in the RMP table. 2. Validate the page after its successfully added in the RMP table. To maintain the security guarantees, if the page is transitioned from private to shared, then perform the following before clearing the encryption attribute from the page table. 1. Invalidate the page. 2. Issue the page state change VMGEXIT to make the page shared in the RMP table. early_set_memory_{encrypted,decrypted}() can be called before the GHCB is setup so use the SNP page state MSR protocol VMGEXIT defined in the GHCB specification to request the page state change in the RMP table. While at it, add a helper snp_prep_memory() which will be used in probe_roms(), in a later patch. [ bp: Massage commit message. ] Signed-off-by: Brijesh Singh <brijesh.singh@amd.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Venu Busireddy <venu.busireddy@oracle.com> Link: https://lore.kernel.org/r/20220307213356.2797205-19-brijesh.singh@amd.com
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1e8c5971 |
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22-Feb-2022 |
Brijesh Singh <brijesh.singh@amd.com> |
x86/mm/cpa: Generalize __set_memory_enc_pgtable() The kernel provides infrastructure to set or clear the encryption mask from the pages for AMD SEV, but TDX requires few tweaks. - TDX and SEV have different requirements to the cache and TLB flushing. - TDX has own routine to notify VMM about page encryption status change. Modify __set_memory_enc_pgtable() and make it flexible enough to cover both AMD SEV and Intel TDX. The AMD-specific behavior is isolated in the callbacks under x86_platform.guest. TDX will provide own version of said callbacks. [ bp: Beat into submission. ] Signed-off-by: Brijesh Singh <brijesh.singh@amd.com> Signed-off-by: Borislav Petkov <bp@suse.de> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Link: https://lore.kernel.org/r/20220223043528.2093214-1-brijesh.singh@amd.com
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20f07a04 |
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06-Dec-2021 |
Kirill A. Shutemov <kirill.shutemov@linux.intel.com> |
x86/sev: Move common memory encryption code to mem_encrypt.c SEV and TDX both protect guest memory from host accesses. They both use guest physical address bits to communicate to the hardware which pages receive protection or not. SEV and TDX both assume that all I/O (real devices and virtio) must be performed to pages *without* protection. To add this support, AMD SEV code forces force_dma_unencrypted() to decrypt DMA pages when DMA pages were allocated for I/O. It also uses swiotlb_update_mem_attributes() to update decryption bits in SWIOTLB DMA buffers. Since TDX also uses a similar memory sharing design, all the above mentioned changes can be reused. So move force_dma_unencrypted(), SWIOTLB update code and virtio changes out of mem_encrypt_amd.c to mem_encrypt.c. Introduce a new config option X86_MEM_ENCRYPT that can be selected by platforms which use x86 memory encryption features (needed in both AMD SEV and Intel TDX guest platforms). Since the code is moved from mem_encrypt_amd.c, inherit the same make flags. This is preparation for enabling TDX memory encryption support and it has no functional changes. Co-developed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Andi Kleen <ak@linux.intel.com> Reviewed-by: Tony Luck <tony.luck@intel.com> Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com> Tested-by: Tom Lendacky <thomas.lendacky@amd.com> Link: https://lore.kernel.org/r/20211206135505.75045-4-kirill.shutemov@linux.intel.com
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dbca5e1a |
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06-Dec-2021 |
Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> |
x86/sev: Rename mem_encrypt.c to mem_encrypt_amd.c Both Intel TDX and AMD SEV implement memory encryption features. But the bulk of the code in mem_encrypt.c is AMD-specific. Rename the file to mem_encrypt_amd.c. A subsequent patch will extract the parts that can be shared by both TDX and AMD SEV/SME into a generic file. No functional changes. Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Tony Luck <tony.luck@intel.com> Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com> Tested-by: Tom Lendacky <thomas.lendacky@amd.com> Link: https://lore.kernel.org/r/20211206135505.75045-3-kirill.shutemov@linux.intel.com
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