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Commitcc5851c6be("KVM: selftests: Use exception fixup for #UD/#GP Hyper-V MSR/hcall tests") introduced a wrong guest assert in guest_hcall(). It is not checking the successful hypercall results and only checks the result when a fault happens. GUEST_ASSERT_2(!hcall->ud_expected || res == hcall->expect, hcall->expect, res); Correct the assertion by only checking results of the successful hypercalls. This issue was observed when this test started failing after building it in Clang. Above guest assert statement fails because "res" is not equal to "hcall->expect" when "hcall->ud_expected" is true. "res" gets some garbage value in Clang from the RAX register. In GCC, RAX is 0 because it using RAX for @output_address in the asm statement and resetting it to 0 before using it as output operand in the same asm statement. Clang is not using RAX for @output_address. Fixes:cc5851c6be("KVM: selftests: Use exception fixup for #UD/#GP Hyper-V MSR/hcall tests") Signed-off-by: Vipin Sharma <vipinsh@google.com> Suggested-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Jim Mattson <jmattson@google.com> Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com> Link: https://lore.kernel.org/r/20220922062451.2927010-1-vipinsh@google.com [sean: wrap changelog at ~75 chars, move -EFAULT change to separate patch] Signed-off-by: Sean Christopherson <seanjc@google.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.