set_memory_p() is currently static.  It has parameters that don't
match set_memory_p() under arch/powerpc and that aren't congruent
with the other set_memory_* functions. There's no good reason for
the difference.

Fix this by making the parameters consistent, and update the one
existing call site.  Make the function non-static and add it to
include/asm/set_memory.h so that it is completely parallel to
set_memory_np() and is usable in other modules.

No functional change.

Signed-off-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Link: https://lore.kernel.org/r/20240116022008.1023398-3-mhklinux@outlook.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <20240116022008.1023398-3-mhklinux@outlook.com>

Pull x86 fixes from Borislav Petkov:

 - Make sure clearing CPU buffers using VERW happens at the latest
   possible point in the return-to-userspace path, otherwise memory
   accesses after the VERW execution could cause data to land in CPU
   buffers again

* tag 'x86_urgent_for_v6.8_rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  KVM/VMX: Move VERW closer to VMentry for MDS mitigation
  KVM/VMX: Use BT+JNC, i.e. EFLAGS.CF to select VMRESUME vs. VMLAUNCH
  x86/bugs: Use ALTERNATIVE() instead of mds_user_clear static key
  x86/entry_32: Add VERW just before userspace transition
  x86/entry_64: Add VERW just before userspace transition
  x86/bugs: Add asm helpers for executing VERW

Daniel Borkmann says:

====================
pull-request: bpf 2024-02-22

The following pull-request contains BPF updates for your *net* tree.

We've added 11 non-merge commits during the last 24 day(s) which contain
a total of 15 files changed, 217 insertions(+), 17 deletions(-).

The main changes are:

1) Fix a syzkaller-triggered oops when attempting to read the vsyscall
   page through bpf_probe_read_kernel and friends, from Hou Tao.

2) Fix a kernel panic due to uninitialized iter position pointer in
   bpf_iter_task, from Yafang Shao.

3) Fix a race between bpf_timer_cancel_and_free and bpf_timer_cancel,
   from Martin KaFai Lau.

4) Fix a xsk warning in skb_add_rx_frag() (under CONFIG_DEBUG_NET)
   due to incorrect truesize accounting, from Sebastian Andrzej Siewior.

5) Fix a NULL pointer dereference in sk_psock_verdict_data_ready,
   from Shigeru Yoshida.

6) Fix a resolve_btfids warning when bpf_cpumask symbol cannot be
   resolved, from Hari Bathini.

bpf-for-netdev

* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf:
  bpf, sockmap: Fix NULL pointer dereference in sk_psock_verdict_data_ready()
  selftests/bpf: Add negtive test cases for task iter
  bpf: Fix an issue due to uninitialized bpf_iter_task
  selftests/bpf: Test racing between bpf_timer_cancel_and_free and bpf_timer_cancel
  bpf: Fix racing between bpf_timer_cancel_and_free and bpf_timer_cancel
  selftest/bpf: Test the read of vsyscall page under x86-64
  x86/mm: Disallow vsyscall page read for copy_from_kernel_nofault()
  x86/mm: Move is_vsyscall_vaddr() into asm/vsyscall.h
  bpf, scripts: Correct GPL license name
  xsk: Add truesize to skb_add_rx_frag().
  bpf: Fix warning for bpf_cpumask in verifier
====================

Link: https://lore.kernel.org/r/20240221231826.1404-1-daniel@iogearbox.net
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

The VERW mitigation at exit-to-user is enabled via a static branch
mds_user_clear. This static branch is never toggled after boot, and can
be safely replaced with an ALTERNATIVE() which is convenient to use in
asm.

Switch to ALTERNATIVE() to use the VERW mitigation late in exit-to-user
path. Also remove the now redundant VERW in exc_nmi() and
arch_exit_to_user_mode().

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/all/20240213-delay-verw-v8-4-a6216d83edb7%40linux.intel.com

MDS mitigation requires clearing the CPU buffers before returning to
user. This needs to be done late in the exit-to-user path. Current
location of VERW leaves a possibility of kernel data ending up in CPU
buffers for memory accesses done after VERW such as:

  1. Kernel data accessed by an NMI between VERW and return-to-user can
     remain in CPU buffers since NMI returning to kernel does not
     execute VERW to clear CPU buffers.
  2. Alyssa reported that after VERW is executed,
     CONFIG_GCC_PLUGIN_STACKLEAK=y scrubs the stack used by a system
     call. Memory accesses during stack scrubbing can move kernel stack
     contents into CPU buffers.
  3. When caller saved registers are restored after a return from
     function executing VERW, the kernel stack accesses can remain in
     CPU buffers(since they occur after VERW).

To fix this VERW needs to be moved very late in exit-to-user path.

In preparation for moving VERW to entry/exit asm code, create macros
that can be used in asm. Also make VERW patching depend on a new feature
flag X86_FEATURE_CLEAR_CPU_BUF.

Reported-by: Alyssa Milburn <alyssa.milburn@intel.com>
Suggested-by: Andrew Cooper <andrew.cooper3@citrix.com>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/all/20240213-delay-verw-v8-1-a6216d83edb7%40linux.intel.com

Move is_vsyscall_vaddr() into asm/vsyscall.h to make it available for
copy_from_kernel_nofault_allowed() in arch/x86/mm/maccess.c.

Reviewed-by: Sohil Mehta <sohil.mehta@intel.com>
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20240202103935.3154011-2-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

We've had issues with gcc and 'asm goto' before, and we created a
'asm_volatile_goto()' macro for that in the past: see commits
3f0116c3238a ("compiler/gcc4: Add quirk for 'asm goto' miscompilation
bug") and a9f180345f53 ("compiler/gcc4: Make quirk for
asm_volatile_goto() unconditional").

Then, much later, we ended up removing the workaround in commit
43c249ea0b1e ("compiler-gcc.h: remove ancient workaround for gcc PR
58670") because we no longer supported building the kernel with the
affected gcc versions, but we left the macro uses around.

Now, Sean Christopherson reports a new version of a very similar
problem, which is fixed by re-applying that ancient workaround.  But the
problem in question is limited to only the 'asm goto with outputs'
cases, so instead of re-introducing the old workaround as-is, let's
rename and limit the workaround to just that much less common case.

It looks like there are at least two separate issues that all hit in
this area:

 (a) some versions of gcc don't mark the asm goto as 'volatile' when it
     has outputs:

        https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98619
        https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110420

     which is easy to work around by just adding the 'volatile' by hand.

 (b) Internal compiler errors:

        https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110422

     which are worked around by adding the extra empty 'asm' as a
     barrier, as in the original workaround.

but the problem Sean sees may be a third thing since it involves bad
code generation (not an ICE) even with the manually added 'volatile'.

but the same old workaround works for this case, even if this feels a
bit like voodoo programming and may only be hiding the issue.

Reported-and-tested-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/all/20240208220604.140859-1-seanjc@google.com/
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Uros Bizjak <ubizjak@gmail.com>
Cc: Jakub Jelinek <jakub@redhat.com>
Cc: Andrew Pinski <quic_apinski@quicinc.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull kvm fixes from Paolo Bonzini:
 "x86 guest:

   - Avoid false positive for check that only matters on AMD processors

  x86:

   - Give a hint when Win2016 might fail to boot due to XSAVES &&
     !XSAVEC configuration

   - Do not allow creating an in-kernel PIT unless an IOAPIC already
     exists

  RISC-V:

   - Allow ISA extensions that were enabled for bare metal in 6.8 (Zbc,
     scalar and vector crypto, Zfh[min], Zihintntl, Zvfh[min], Zfa)

  S390:

   - fix CC for successful PQAP instruction

   - fix a race when creating a shadow page"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  x86/coco: Define cc_vendor without CONFIG_ARCH_HAS_CC_PLATFORM
  x86/kvm: Fix SEV check in sev_map_percpu_data()
  KVM: x86: Give a hint when Win2016 might fail to boot due to XSAVES erratum
  KVM: x86: Check irqchip mode before create PIT
  KVM: riscv: selftests: Add Zfa extension to get-reg-list test
  RISC-V: KVM: Allow Zfa extension for Guest/VM
  KVM: riscv: selftests: Add Zvfh[min] extensions to get-reg-list test
  RISC-V: KVM: Allow Zvfh[min] extensions for Guest/VM
  KVM: riscv: selftests: Add Zihintntl extension to get-reg-list test
  RISC-V: KVM: Allow Zihintntl extension for Guest/VM
  KVM: riscv: selftests: Add Zfh[min] extensions to get-reg-list test
  RISC-V: KVM: Allow Zfh[min] extensions for Guest/VM
  KVM: riscv: selftests: Add vector crypto extensions to get-reg-list test
  RISC-V: KVM: Allow vector crypto extensions for Guest/VM
  KVM: riscv: selftests: Add scaler crypto extensions to get-reg-list test
  RISC-V: KVM: Allow scalar crypto extensions for Guest/VM
  KVM: riscv: selftests: Add Zbc extension to get-reg-list test
  RISC-V: KVM: Allow Zbc extension for Guest/VM
  KVM: s390: fix cc for successful PQAP
  KVM: s390: vsie: fix race during shadow creation

After commit a9ef277488cf ("x86/kvm: Fix SEV check in
sev_map_percpu_data()"), there is a build error when building
x86_64_defconfig with GCOV using LLVM:

  ld.lld: error: undefined symbol: cc_vendor
  >>> referenced by kvm.c
  >>>               arch/x86/kernel/kvm.o:(kvm_smp_prepare_boot_cpu) in archive vmlinux.a

which corresponds to

  if (cc_vendor != CC_VENDOR_AMD ||
      !cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
            return;

Without GCOV, clang is able to eliminate the use of cc_vendor because
cc_platform_has() evaluates to false when CONFIG_ARCH_HAS_CC_PLATFORM is
not set, meaning that if statement will be true no matter what value
cc_vendor has.

With GCOV, the instrumentation keeps the use of cc_vendor around for
code coverage purposes but cc_vendor is only declared, not defined,
without CONFIG_ARCH_HAS_CC_PLATFORM, leading to the build error above.

Provide a macro definition of cc_vendor when CONFIG_ARCH_HAS_CC_PLATFORM
is not set with a value of CC_VENDOR_NONE, so that the first condition
can always be evaluated/eliminated at compile time, avoiding the build
error altogether. This is very similar to the situation prior to
commit da86eb961184 ("x86/coco: Get rid of accessor functions").

Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Borislav Petkov (AMD) <bp@alien8.de>
Message-Id: <20240202-provide-cc_vendor-without-arch_has_cc_platform-v1-1-09ad5f2a3099@kernel.org>
Fixes: a9ef277488cf ("x86/kvm: Fix SEV check in sev_map_percpu_data()", 2024-01-31)
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Since commit b0563468eeac ("x86/CPU/AMD: Disable XSAVES on AMD family 0x17")
kernel unconditionally clears the XSAVES CPU feature bit on Zen1/2 CPUs.

Because KVM CPU caps are initialized from the kernel boot CPU features this
makes the XSAVES feature also unavailable for KVM guests in this case.
At the same time the XSAVEC feature is left enabled.

Unfortunately, having XSAVEC but no XSAVES in CPUID breaks Hyper-V enabled
Windows Server 2016 VMs that have more than one vCPU.

Let's at least give users hint in the kernel log what could be wrong since
these VMs currently simply hang at boot with a black screen - giving no
clue what suddenly broke them and how to make them work again.

Trigger the kernel message hint based on the particular guest ID written to
the Guest OS Identity Hyper-V MSR implemented by KVM.

Defer this check to when the L1 Hyper-V hypervisor enables SVM in EFER
since we want to limit this message to Hyper-V enabled Windows guests only
(Windows session running nested as L2) but the actual Guest OS Identity MSR
write is done by L1 and happens before it enables SVM.

Fixes: b0563468eeac ("x86/CPU/AMD: Disable XSAVES on AMD family 0x17")
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Message-Id: <b83ab45c5e239e5d148b0ae7750133a67ac9575c.1706127425.git.maciej.szmigiero@oracle.com>
[Move some checks before mutex_lock(), rename function. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>