pm24.git/arch/x86/coco/tdx, branch master

x86/tdx: Enable CPU topology enumeration

2024-11-07T18:27:45Z

TDX 1.0 defines baseline behaviour of TDX guest platform. TDX 1.0 generates a #VE when accessing topology-related CPUID leafs (0xB and 0x1F) and the X2APIC_APICID MSR. The kernel returns all zeros on CPUID topology. In practice, this means that the kernel can only boot with a plain topology. Any complications will cause problems. The ENUM_TOPOLOGY feature allows the VMM to provide topology information to the guest. Enabling the feature eliminates topology-related #VEs: the TDX module virtualizes accesses to the CPUID leafs and the MSR. Enable ENUM_TOPOLOGY if it is available. Signed-off-by: Kirill A. Shutemov Signed-off-by: Dave Hansen Acked-by: Kai Huang Link: https://lore.kernel.org/all/20241104103803.195705-5-kirill.shutemov%40linux.intel.com

x86/tdx: Dynamically disable SEPT violations from causing #VEs

2024-11-07T18:27:38Z

Memory access #VEs are hard for Linux to handle in contexts like the entry code or NMIs. But other OSes need them for functionality. There's a static (pre-guest-boot) way for a VMM to choose one or the other. But VMMs don't always know which OS they are booting, so they choose to deliver those #VEs so the "other" OSes will work. That, unfortunately has left us in the lurch and exposed to these hard-to-handle #VEs. The TDX module has introduced a new feature. Even if the static configuration is set to "send nasty #VEs", the kernel can dynamically request that they be disabled. Once they are disabled, access to private memory that is not in the Mapped state in the Secure-EPT (SEPT) will result in an exit to the VMM rather than injecting a #VE. Check if the feature is available and disable SEPT #VE if possible. If the TD is allowed to disable/enable SEPT #VEs, the ATTR_SEPT_VE_DISABLE attribute is no longer reliable. It reflects the initial state of the control for the TD, but it will not be updated if someone (e.g. bootloader) changes it before the kernel starts. Kernel must check TDCS_TD_CTLS bit to determine if SEPT #VEs are enabled or disabled. [ dhansen: remove 'return' at end of function ] Fixes: 373e715e31bf ("x86/tdx: Panic on bad configs that #VE on "private" memory access") Signed-off-by: Kirill A. Shutemov Signed-off-by: Dave Hansen Acked-by: Kai Huang Link: https://lore.kernel.org/all/20241104103803.195705-4-kirill.shutemov%40linux.intel.com

x86/tdx: Rename tdx_parse_tdinfo() to tdx_setup()

2024-11-07T18:26:37Z

Rename tdx_parse_tdinfo() to tdx_setup() and move setting NOTIFY_ENABLES there. The function will be extended to adjust TD configuration. Signed-off-by: Kirill A. Shutemov Signed-off-by: Dave Hansen Reviewed-by: Kuppuswamy Sathyanarayanan Reviewed-by: Kai Huang Link: https://lore.kernel.org/all/20241104103803.195705-3-kirill.shutemov%40linux.intel.com

x86/tdx: Introduce wrappers to read and write TD metadata

2024-11-07T18:26:16Z

The TDG_VM_WR TDCALL is used to ask the TDX module to change some TD-specific VM configuration. There is currently only one user in the kernel of this TDCALL leaf. More will be added shortly. Refactor to make way for more users of TDG_VM_WR who will need to modify other TD configuration values. Add a wrapper for the TDG_VM_RD TDCALL that requests TD-specific metadata from the TDX module. There are currently no users for TDG_VM_RD. Mark it as __maybe_unused until the first user appears. This is preparation for enumeration and enabling optional TD features. Signed-off-by: Kirill A. Shutemov Signed-off-by: Dave Hansen Reviewed-by: Kai Huang Reviewed-by: Kuppuswamy Sathyanarayanan Link: https://lore.kernel.org/all/20241104103803.195705-2-kirill.shutemov%40linux.intel.com

x86/tdx: Fix "in-kernel MMIO" check

2024-09-26T16:45:04Z

TDX only supports kernel-initiated MMIO operations. The handle_mmio() function checks if the #VE exception occurred in the kernel and rejects the operation if it did not. However, userspace can deceive the kernel into performing MMIO on its behalf. For example, if userspace can point a syscall to an MMIO address, syscall does get_user() or put_user() on it, triggering MMIO #VE. The kernel will treat the #VE as in-kernel MMIO. Ensure that the target MMIO address is within the kernel before decoding instruction. Fixes: 31d58c4e557d ("x86/tdx: Handle in-kernel MMIO") Signed-off-by: Alexey Gladkov (Intel) Signed-off-by: Dave Hansen Reviewed-by: Kirill A. Shutemov Acked-by: Dave Hansen Cc:stable@vger.kernel.org Link: https://lore.kernel.org/all/565a804b80387970460a4ebc67c88d1380f61ad1.1726237595.git.legion%40kernel.org

x86/tdx: Fix data leak in mmio_read()

2024-08-26T19:45:19Z

The mmio_read() function makes a TDVMCALL to retrieve MMIO data for an address from the VMM. Sean noticed that mmio_read() unintentionally exposes the value of an initialized variable (val) on the stack to the VMM. This variable is only needed as an output value. It did not need to be passed to the VMM in the first place. Do not send the original value of *val to the VMM. [ dhansen: clarify what 'val' is used for. ] Fixes: 31d58c4e557d ("x86/tdx: Handle in-kernel MMIO") Reported-by: Sean Christopherson Signed-off-by: Kirill A. Shutemov Signed-off-by: Dave Hansen Cc:stable@vger.kernel.org Link: https://lore.kernel.org/all/20240826125304.1566719-1-kirill.shutemov%40linux.intel.com

x86/tdx: Convert shared memory back to private on kexec

2024-06-17T15:46:05Z

TDX guests allocate shared buffers to perform I/O. It is done by allocating pages normally from the buddy allocator and converting them to shared with set_memory_decrypted(). The second, kexec-ed kernel has no idea what memory is converted this way. It only sees E820_TYPE_RAM. Accessing shared memory via private mapping is fatal. It leads to unrecoverable TD exit. On kexec, walk direct mapping and convert all shared memory back to private. It makes all RAM private again and second kernel may use it normally. The conversion occurs in two steps: stopping new conversions and unsharing all memory. In the case of normal kexec, the stopping of conversions takes place while scheduling is still functioning. This allows for waiting until any ongoing conversions are finished. The second step is carried out when all CPUs except one are inactive and interrupts are disabled. This prevents any conflicts with code that may access shared memory. Signed-off-by: Kirill A. Shutemov Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Rick Edgecombe Reviewed-by: Kai Huang Tested-by: Tao Liu Link: https://lore.kernel.org/r/20240614095904.1345461-12-kirill.shutemov@linux.intel.com

x86/tdx: Account shared memory

2024-06-17T15:45:59Z

The kernel will convert all shared memory back to private during kexec. The direct mapping page tables will provide information on which memory is shared. It is extremely important to convert all shared memory. If a page is missed, it will cause the second kernel to crash when it accesses it. Keep track of the number of shared pages. This will allow for cross-checking against the shared information in the direct mapping and reporting if the shared bit is lost. Memory conversion is slow and does not happen often. Global atomic is not going to be a bottleneck. Signed-off-by: Kirill A. Shutemov Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Kai Huang Tested-by: Tao Liu Link: https://lore.kernel.org/r/20240614095904.1345461-10-kirill.shutemov@linux.intel.com

x86/mm: Make x86_platform.guest.enc_status_change_*() return an error

2024-06-17T15:45:53Z

TDX is going to have more than one reason to fail enc_status_change_prepare(). Change the callback to return errno instead of assuming -EIO. Change enc_status_change_finish() too to keep the interface symmetric. Signed-off-by: Kirill A. Shutemov Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Dave Hansen Reviewed-by: Kai Huang Reviewed-by: Michael Kelley Tested-by: Tao Liu Link: https://lore.kernel.org/r/20240614095904.1345461-8-kirill.shutemov@linux.intel.com

Merge tag 'x86_tdx_for_6.8' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2024-01-18T21:41:48Z

Pull x86 TDX updates from Dave Hansen: "This contains the initial support for host-side TDX support so that KVM can run TDX-protected guests. This does not include the actual KVM-side support which will come from the KVM folks. The TDX host interactions with kexec also needs to be ironed out before this is ready for prime time, so this code is currently Kconfig'd off when kexec is on. The majority of the code here is the kernel telling the TDX module which memory to protect and handing some additional memory over to it to use to store TDX module metadata. That sounds pretty simple, but the TDX architecture is rather flexible and it takes quite a bit of back-and-forth to say, "just protect all memory, please." There is also some code tacked on near the end of the series to handle a hardware erratum. The erratum can make software bugs such as a kernel write to TDX-protected memory cause a machine check and masquerade as a real hardware failure. The erratum handling watches out for these and tries to provide nicer user errors" * tag 'x86_tdx_for_6.8' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (21 commits) x86/virt/tdx: Make TDX host depend on X86_MCE x86/virt/tdx: Disable TDX host support when kexec is enabled Documentation/x86: Add documentation for TDX host support x86/mce: Differentiate real hardware #MCs from TDX erratum ones x86/cpu: Detect TDX partial write machine check erratum x86/virt/tdx: Handle TDX interaction with sleep and hibernation x86/virt/tdx: Initialize all TDMRs x86/virt/tdx: Configure global KeyID on all packages x86/virt/tdx: Configure TDX module with the TDMRs and global KeyID x86/virt/tdx: Designate reserved areas for all TDMRs x86/virt/tdx: Allocate and set up PAMTs for TDMRs x86/virt/tdx: Fill out TDMRs to cover all TDX memory regions x86/virt/tdx: Add placeholder to construct TDMRs to cover all TDX memory regions x86/virt/tdx: Get module global metadata for module initialization x86/virt/tdx: Use all system memory when initializing TDX module as TDX memory x86/virt/tdx: Add skeleton to enable TDX on demand x86/virt/tdx: Add SEAMCALL error printing for module initialization x86/virt/tdx: Handle SEAMCALL no entropy error in common code x86/virt/tdx: Make INTEL_TDX_HOST depend on X86_X2APIC x86/virt/tdx: Define TDX supported page sizes as macros ...