kernel.git/arch/x86/include, branch linux-6.4.y

x86/sev: Make enc_dec_hypercall() accept a size instead of npages

2023-09-13T07:48:41Z

commit ac3f9c9f1b37edaa7d1a9b908bc79d843955a1a2 upstream. 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 Signed-off-by: Ingo Molnar Reviewed-by: Tom Lendacky Reviewed-by: Pankaj Gupta Tested-by: Ben Hillier Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20230824223731.2055016-1-srutherford@google.com Signed-off-by: Greg Kroah-Hartman

x86/mm: Fix PAT bit missing from page protection modify mask

2023-09-13T07:48:13Z

[ Upstream commit 548cb932051fb6232ac983ed6673dae7bdf3cf4c ] Visible glitches have been observed when running graphics applications on Linux under Xen hypervisor. Those observations have been confirmed with failures from kms_pwrite_crc Intel GPU test that verifies data coherency of DRM frame buffer objects using hardware CRC checksums calculated by display controllers, exposed to userspace via debugfs. Affected processing paths have then been identified with new IGT test variants that mmap the objects using different methods and caching modes [1]. When running as a Xen PV guest, Linux uses Xen provided PAT configuration which is different from its native one. In particular, Xen specific PTE encoding of write-combining caching, likely used by graphics applications, differs from the Linux default one found among statically defined minimal set of supported modes. Since Xen defines PTE encoding of the WC mode as _PAGE_PAT, it no longer belongs to the minimal set, depends on correct handling of _PAGE_PAT bit, and can be mismatched with write-back caching. When a user calls mmap() for a DRM buffer object, DRM device specific .mmap file operation, called from mmap_region(), takes care of setting PTE encoding bits in a vm_page_prot field of an associated virtual memory area structure. Unfortunately, _PAGE_PAT bit is not preserved when the vma's .vm_flags are then applied to .vm_page_prot via vm_set_page_prot(). Bits to be preserved are determined with _PAGE_CHG_MASK symbol that doesn't cover _PAGE_PAT. As a consequence, WB caching is requested instead of WC when running under Xen (also, WP is silently changed to WT, and UC downgraded to UC_MINUS). When running on bare metal, WC is not affected, but WP and WT extra modes are unintentionally replaced with WC and UC, respectively. WP and WT modes, encoded with _PAGE_PAT bit set, were introduced by commit 281d4078bec3 ("x86: Make page cache mode a real type"). Care was taken to extend _PAGE_CACHE_MASK symbol with that additional bit, but that symbol has never been used for identification of bits preserved when applying page protection flags. Support for all cache modes under Xen, including the problematic WC mode, was then introduced by commit 47591df50512 ("xen: Support Xen pv-domains using PAT"). The issue needs to be fixed by including _PAGE_PAT bit into a bitmask used by pgprot_modify() for selecting bits to be preserved. We can do that either internally to pgprot_modify() (as initially proposed), or by making _PAGE_PAT a part of _PAGE_CHG_MASK. If we go for the latter then, since _PAGE_PAT is the same as _PAGE_PSE, we need to note that _HPAGE_CHG_MASK -- a huge pmds' counterpart of _PAGE_CHG_MASK, introduced by commit c489f1257b8c ("thp: add pmd_modify"), defined as (_PAGE_CHG_MASK | _PAGE_PSE) -- will no longer differ from _PAGE_CHG_MASK. If such modification of _PAGE_CHG_MASK was irrelevant to its users then one might wonder why that new _HPAGE_CHG_MASK symbol was introduced instead of reusing the existing one with that otherwise irrelevant bit (_PAGE_PSE in that case) added. Add _PAGE_PAT to _PAGE_CHG_MASK and _PAGE_PAT_LARGE to _HPAGE_CHG_MASK for symmetry. Split out common bits from both symbols to a common symbol for clarity. [ dhansen: tweak the solution changelog description ] [1] https://gitlab.freedesktop.org/drm/igt-gpu-tools/-/commit/0f0754413f14 Fixes: 281d4078bec3 ("x86: Make page cache mode a real type") Signed-off-by: Janusz Krzysztofik Signed-off-by: Dave Hansen Reviewed-by: Andi Shyti Reviewed-by: Juergen Gross Tested-by: Marek Marczykowski-Górecki Link: https://gitlab.freedesktop.org/drm/intel/-/issues/7648 Link: https://lore.kernel.org/all/20230710073613.8006-2-janusz.krzysztofik%40linux.intel.com Signed-off-by: Sasha Levin

locking/arch: Avoid variable shadowing in local_try_cmpxchg()

2023-09-13T07:47:57Z

[ Upstream commit d6b45484c130f4095313ae3edeb4aae662c12fb1 ] Several architectures define arch_try_local_cmpxchg macro using internal temporary variables named ___old, __old or _old. Remove temporary varible in local_try_cmpxchg to avoid variable shadowing. No functional change intended. Fixes: d994f2c8e241 ("locking/arch: Wire up local_try_cmpxchg()") Closes: https://lore.kernel.org/lkml/CAFGhKbyxtuk=LoW-E3yLXgcmR93m+Dfo5-u9oQA_YC5Fcy_t9g@mail.gmail.com/ Reported-by: Charlemagne Lasse Signed-off-by: Uros Bizjak Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20230708090048.63046-1-ubizjak@gmail.com Signed-off-by: Sasha Levin

lockdep: fix static memory detection even more

2023-09-02T07:14:38Z

commit 0a6b58c5cd0dfd7961e725212f0fc8dfc5d96195 upstream. On the parisc architecture, lockdep reports for all static objects which are in the __initdata section (e.g. "setup_done" in devtmpfs, "kthreadd_done" in init/main.c) this warning: INFO: trying to register non-static key. The warning itself is wrong, because those objects are in the __initdata section, but the section itself is on parisc outside of range from _stext to _end, which is why the static_obj() functions returns a wrong answer. While fixing this issue, I noticed that the whole existing check can be simplified a lot. Instead of checking against the _stext and _end symbols (which include code areas too) just check for the .data and .bss segments (since we check a data object). This can be done with the existing is_kernel_core_data() macro. In addition objects in the __initdata section can be checked with init_section_contains(), and is_kernel_rodata() allows keys to be in the _ro_after_init section. This partly reverts and simplifies commit bac59d18c701 ("x86/setup: Fix static memory detection"). Link: https://lkml.kernel.org/r/ZNqrLRaOi/3wPAdp@p100 Fixes: bac59d18c701 ("x86/setup: Fix static memory detection") Signed-off-by: Helge Deller Cc: Borislav Petkov Cc: Greg Kroah-Hartman Cc: Guenter Roeck Cc: Peter Zijlstra Cc: "Rafael J. Wysocki" Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

x86/retpoline,kprobes: Skip optprobe check for indirect jumps with retpolines and IBT

2023-08-23T15:32:41Z

commit 833fd800bf56b74d39d71d3f5936dffb3e0409c6 upstream. The kprobes optimization check can_optimize() calls insn_is_indirect_jump() to detect indirect jump instructions in a target function. If any is found, creating an optprobe is disallowed in the function because the jump could be from a jump table and could potentially land in the middle of the target optprobe. With retpolines, insn_is_indirect_jump() additionally looks for calls to indirect thunks which the compiler potentially used to replace original jumps. This extra check is however unnecessary because jump tables are disabled when the kernel is built with retpolines. The same is currently the case with IBT. Based on this observation, remove the logic to look for calls to indirect thunks and skip the check for indirect jumps altogether if the kernel is built with retpolines or IBT. Remove subsequently the symbols __indirect_thunk_start and __indirect_thunk_end which are no longer needed. Dropping this logic indirectly fixes a problem where the range [__indirect_thunk_start, __indirect_thunk_end] wrongly included also the return thunk. It caused that machines which used the return thunk as a mitigation and didn't have it patched by any alternative ended up not being able to use optprobes in any regular function. Fixes: 0b53c374b9ef ("x86/retpoline: Use -mfunction-return") Suggested-by: Peter Zijlstra (Intel) Suggested-by: Masami Hiramatsu (Google) Signed-off-by: Petr Pavlu Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Borislav Petkov (AMD) Acked-by: Masami Hiramatsu (Google) Link: https://lore.kernel.org/r/20230711091952.27944-3-petr.pavlu@suse.com Signed-off-by: Greg Kroah-Hartman

x86/CPU/AMD: Fix the DIV(0) initial fix attempt

2023-08-23T15:32:41Z

commit f58d6fbcb7c848b7f2469be339bc571f2e9d245b upstream. Initially, it was thought that doing an innocuous division in the #DE handler would take care to prevent any leaking of old data from the divider but by the time the fault is raised, the speculation has already advanced too far and such data could already have been used by younger operations. Therefore, do the innocuous division on every exit to userspace so that userspace doesn't see any potentially old data from integer divisions in kernel space. Do the same before VMRUN too, to protect host data from leaking into the guest too. Fixes: 77245f1c3c64 ("x86/CPU/AMD: Do not leak quotient data after a division by 0") Signed-off-by: Borislav Petkov (AMD) Cc: Link: https://lore.kernel.org/r/20230811213824.10025-1-bp@alien8.de Signed-off-by: Greg Kroah-Hartman

x86/cpu/kvm: Provide UNTRAIN_RET_VM

2023-08-23T15:32:40Z

commit 864bcaa38ee44ec6c0e43f79c2d2997b977e26b2 upstream. Similar to how it doesn't make sense to have UNTRAIN_RET have two untrain calls, it also doesn't make sense for VMEXIT to have an extra IBPB call. This cures VMEXIT doing potentially unret+IBPB or double IBPB. Also, the (SEV) VMEXIT case seems to have been overlooked. Redefine the meaning of the synthetic IBPB flags to: - ENTRY_IBPB -- issue IBPB on entry (was: entry + VMEXIT) - IBPB_ON_VMEXIT -- issue IBPB on VMEXIT And have 'retbleed=ibpb' set *BOTH* feature flags to ensure it retains the previous behaviour and issues IBPB on entry+VMEXIT. The new 'srso=ibpb_vmexit' option only sets IBPB_ON_VMEXIT. Create UNTRAIN_RET_VM specifically for the VMEXIT case, and have that check IBPB_ON_VMEXIT. All this avoids having the VMEXIT case having to check both ENTRY_IBPB and IBPB_ON_VMEXIT and simplifies the alternatives. Fixes: fb3bd914b3ec ("x86/srso: Add a Speculative RAS Overflow mitigation") Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/r/20230814121149.109557833@infradead.org Signed-off-by: Greg Kroah-Hartman

x86/cpu: Cleanup the untrain mess

2023-08-23T15:32:40Z

commit e7c25c441e9e0fa75b4c83e0b26306b702cfe90d upstream. Since there can only be one active return_thunk, there only needs be one (matching) untrain_ret. It fundamentally doesn't make sense to allow multiple untrain_ret at the same time. Fold all the 3 different untrain methods into a single (temporary) helper stub. Fixes: fb3bd914b3ec ("x86/srso: Add a Speculative RAS Overflow mitigation") Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/r/20230814121149.042774962@infradead.org Signed-off-by: Greg Kroah-Hartman

x86/cpu: Rename srso_(.*)_alias to srso_alias_\1

2023-08-23T15:32:40Z

commit 42be649dd1f2eee6b1fb185f1a231b9494cf095f upstream. For a more consistent namespace. [ bp: Fixup names in the doc too. ] Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/r/20230814121148.976236447@infradead.org Signed-off-by: Greg Kroah-Hartman

x86/cpu: Rename original retbleed methods

2023-08-23T15:32:40Z

commit d025b7bac07a6e90b6b98b487f88854ad9247c39 upstream. Rename the original retbleed return thunk and untrain_ret to retbleed_return_thunk() and retbleed_untrain_ret(). No functional changes. Suggested-by: Josh Poimboeuf Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/r/20230814121148.909378169@infradead.org Signed-off-by: Greg Kroah-Hartman