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    Subject[PATCH 5.18 42/61] x86/speculation: Fix firmware entry SPEC_CTRL handling
    Date
    From: Josh Poimboeuf <jpoimboe@kernel.org>

    commit e6aa13622ea8283cc699cac5d018cc40a2ba2010 upstream.

    The firmware entry code may accidentally clear STIBP or SSBD. Fix that.

    Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
    Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
    Signed-off-by: Borislav Petkov <bp@suse.de>
    Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    arch/x86/include/asm/nospec-branch.h | 10 ++++------
    1 file changed, 4 insertions(+), 6 deletions(-)

    --- a/arch/x86/include/asm/nospec-branch.h
    +++ b/arch/x86/include/asm/nospec-branch.h
    @@ -285,18 +285,16 @@ extern u64 spec_ctrl_current(void);
    */
    #define firmware_restrict_branch_speculation_start() \
    do { \
    - u64 val = x86_spec_ctrl_base | SPEC_CTRL_IBRS; \
    - \
    preempt_disable(); \
    - alternative_msr_write(MSR_IA32_SPEC_CTRL, val, \
    + alternative_msr_write(MSR_IA32_SPEC_CTRL, \
    + spec_ctrl_current() | SPEC_CTRL_IBRS, \
    X86_FEATURE_USE_IBRS_FW); \
    } while (0)

    #define firmware_restrict_branch_speculation_end() \
    do { \
    - u64 val = x86_spec_ctrl_base; \
    - \
    - alternative_msr_write(MSR_IA32_SPEC_CTRL, val, \
    + alternative_msr_write(MSR_IA32_SPEC_CTRL, \
    + spec_ctrl_current(), \
    X86_FEATURE_USE_IBRS_FW); \
    preempt_enable(); \
    } while (0)

    \
     
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