Pull x86 SEV updates from Borislav Petkov: - Some SEV and CC platform helpers cleanup and simplifications now that the usage patterns are becoming apparent [ I'm sure I'm the only one that has gets confused by all the TLAs, but in case there are others: here SEV is AMD's "Secure Encrypted Virtualization" and CC is generic "Confidential Computing". There's also Intel SGX (Software Guard Extensions) and TDX (Trust Domain Extensions), along with all the vendor memory encryption extensions (SME, TSME, TME, and WTF). And then we have arm64 with RMA and CCA, and I probably forgot another dozen or so related acronyms - Linus ] * tag 'x86_sev_for_v6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/coco: Get rid of accessor functions x86/sev: Get rid of special sev_es_enable_key x86/coco: Mark cc_platform_has() and descendants noinstr
Pull x86 tdx updates from Dave Hansen: - Fix a race window where load_unaligned_zeropad() could cause a fatal shutdown during TDX private<=>shared conversion The race has never been observed in practice but might allow load_unaligned_zeropad() to catch a TDX page in the middle of its conversion process which would lead to a fatal and unrecoverable guest shutdown. - Annotate sites where VM "exit reasons" are reused as hypercall numbers. * tag 'x86_tdx_for_6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/mm: Fix enc_status_change_finish_noop() x86/tdx: Fix race between set_memory_encrypted() and load_unaligned_zeropad() x86/mm: Allow guest.enc_status_change_prepare() to fail x86/tdx: Wrap exit reason with hcall_func()
Pull x86 confidential computing update from Borislav Petkov: - Add support for unaccepted memory as specified in the UEFI spec v2.9. The gist of it all is that Intel TDX and AMD SEV-SNP confidential computing guests define the notion of accepting memory before using it and thus preventing a whole set of attacks against such guests like memory replay and the like. There are a couple of strategies of how memory should be accepted - the current implementation does an on-demand way of accepting. * tag 'x86_cc_for_v6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: virt: sevguest: Add CONFIG_CRYPTO dependency x86/efi: Safely enable unaccepted memory in UEFI x86/sev: Add SNP-specific unaccepted memory support x86/sev: Use large PSC requests if applicable x86/sev: Allow for use of the early boot GHCB for PSC requests x86/sev: Put PSC struct on the stack in prep for unaccepted memory support x86/sev: Fix calculation of end address based on number of pages x86/tdx: Add unaccepted memory support x86/tdx: Refactor try_accept_one() x86/tdx: Make _tdx_hypercall() and __tdx_module_call() available in boot stub efi/unaccepted: Avoid load_unaligned_zeropad() stepping into unaccepted memory efi: Add unaccepted memory support x86/boot/compressed: Handle unaccepted memory efi/libstub: Implement support for unaccepted memory efi/x86: Get full memory map in allocate_e820() mm: Add support for unaccepted memory
tl;dr: There is a race in the TDX private<=>shared conversion code
which could kill the TDX guest. Fix it by changing conversion
ordering to eliminate the window.
TDX hardware maintains metadata to track which pages are private and
shared. Additionally, TDX guests use the guest x86 page tables to
specify whether a given mapping is intended to be private or shared.
Bad things happen when the intent and metadata do not match.
So there are two thing in play:
1. "the page" -- the physical TDX page metadata
2. "the mapping" -- the guest-controlled x86 page table intent
For instance, an unrecoverable exit to VMM occurs if a guest touches a
private mapping that points to a shared physical page.
In summary:
* Private mapping => Private Page == OK (obviously)
* Shared mapping => Shared Page == OK (obviously)
* Private mapping => Shared Page == BIG BOOM!
* Shared mapping => Private Page == OK-ish
(It will read generate a recoverable #VE via handle_mmio())
Enter load_unaligned_zeropad(). It can touch memory that is adjacent but
otherwise unrelated to the memory it needs to touch. It will cause one
of those unrecoverable exits (aka. BIG BOOM) if it blunders into a
shared mapping pointing to a private page.
This is a problem when __set_memory_enc_pgtable() converts pages from
shared to private. It first changes the mapping and second modifies
the TDX page metadata. It's moving from:
* Shared mapping => Shared Page == OK
to:
* Private mapping => Shared Page == BIG BOOM!
This means that there is a window with a shared mapping pointing to a
private page where load_unaligned_zeropad() can strike.
Add a TDX handler for guest.enc_status_change_prepare(). This converts
the page from shared to private *before* the page becomes private. This
ensures that there is never a private mapping to a shared page.
Leave a guest.enc_status_change_finish() in place but only use it for
private=>shared conversions. This will delay updating the TDX metadata
marking the page private until *after* the mapping matches the metadata.
This also ensures that there is never a private mapping to a shared page.
[ dhansen: rewrite changelog ]
Fixes: 7dbde7631629 ("x86/mm/cpa: Add support for TDX shared memory")
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/20230606095622.1939-3-kirill.shutemov%40linux.intel.com
Hookup TDX-specific code to accept memory. Accepting the memory is done with ACCEPT_PAGE module call on every page in the range. MAP_GPA hypercall is not required as the unaccepted memory is considered private already. Extract the part of tdx_enc_status_changed() that does memory acceptance in a new helper. Move the helper tdx-shared.c. It is going to be used by both main kernel and decompressor. [ bp: Fix the INTEL_TDX_GUEST=y, KVM_GUEST=n build. ] Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Link: https://lore.kernel.org/r/20230606142637.5171-10-kirill.shutemov@linux.intel.com
Rework try_accept_one() to return accepted size instead of modifying 'start' inside the helper. It makes 'start' in-only argument and streamlines code on the caller side. Suggested-by: Borislav Petkov <bp@alien8.de> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com> Link: https://lore.kernel.org/r/20230606142637.5171-9-kirill.shutemov@linux.intel.com
Memory acceptance requires a hypercall and one or multiple module calls. Make helpers for the calls available in boot stub. It has to accept memory where kernel image and initrd are placed. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com> Link: https://lore.kernel.org/r/20230606142637.5171-8-kirill.shutemov@linux.intel.com
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
TDX reuses VMEXIT "reasons" in its guest->host hypercall ABI. This is confusing because there might not be a VMEXIT involved at *all*. These instances are supposed to document situation and reduce confusion by wrapping VMEXIT reasons with hcall_func(). The decompression code does not follow this convention. Unify the TDX decompression code with the other TDX use of VMEXIT reasons. No functional changes. Signed-off-by: Nikolay Borisov <nik.borisov@suse.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Link: https://lore.kernel.org/all/20230505120332.1429957-1-nik.borisov%40suse.com
cc_vendor is __ro_after_init and thus can be used directly. No functional changes. Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Link: https://lore.kernel.org/r/20230508121957.32341-1-bp@alien8.de