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    Subject[PATCH v7 60/72] x86/sev-es: Handle #AC Events
    Date
    From: Joerg Roedel <jroedel@suse.de>

    Implement a handler for #VC exceptions caused by #AC exceptions. The #AC
    exception is just forwarded to do_alignment_check() and not pushed down
    to the hypervisor, as requested by the SEV-ES GHCB Standardization
    Specification.

    Signed-off-by: Joerg Roedel <jroedel@suse.de>
    ---
    arch/x86/kernel/sev-es.c | 19 +++++++++++++++++++
    1 file changed, 19 insertions(+)

    diff --git a/arch/x86/kernel/sev-es.c b/arch/x86/kernel/sev-es.c
    index db8e33280f7a..f78ab9369b9c 100644
    --- a/arch/x86/kernel/sev-es.c
    +++ b/arch/x86/kernel/sev-es.c
    @@ -909,6 +909,19 @@ static enum es_result vc_handle_vmmcall(struct ghcb *ghcb,
    return ES_OK;
    }

    +static enum es_result vc_handle_trap_ac(struct ghcb *ghcb,
    + struct es_em_ctxt *ctxt)
    +{
    + /*
    + * Calling ecx_alignment_check() directly does not work, because it
    + * enables IRQs and the GHCB is active. Forward the exception and call
    + * it later from vc_forward_exception().
    + */
    + ctxt->fi.vector = X86_TRAP_AC;
    + ctxt->fi.error_code = 0;
    + return ES_EXCEPTION;
    +}
    +
    static enum es_result vc_handle_exitcode(struct es_em_ctxt *ctxt,
    struct ghcb *ghcb,
    unsigned long exit_code)
    @@ -922,6 +935,9 @@ static enum es_result vc_handle_exitcode(struct es_em_ctxt *ctxt,
    case SVM_EXIT_WRITE_DR7:
    result = vc_handle_dr7_write(ghcb, ctxt);
    break;
    + case SVM_EXIT_EXCP_BASE + X86_TRAP_AC:
    + result = vc_handle_trap_ac(ghcb, ctxt);
    + break;
    case SVM_EXIT_RDTSC:
    case SVM_EXIT_RDTSCP:
    result = vc_handle_rdtsc(ghcb, ctxt, exit_code);
    @@ -981,6 +997,9 @@ static __always_inline void vc_forward_exception(struct es_em_ctxt *ctxt)
    case X86_TRAP_UD:
    exc_invalid_op(ctxt->regs);
    break;
    + case X86_TRAP_AC:
    + exc_alignment_check(ctxt->regs, error_code);
    + break;
    default:
    pr_emerg("Unsupported exception in #VC instruction emulation - can't continue\n");
    BUG();
    --
    2.28.0
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