• Paul Mackerras's avatar
    KVM: PPC: Book3S HV: Save/restore host values of debug registers · 773853e9
    Paul Mackerras authored
    [ Upstream commit 7ceaa6dc ]
    
    At present, HV KVM on POWER8 and POWER9 machines loses any instruction
    or data breakpoint set in the host whenever a guest is run.
    Instruction breakpoints are currently only used by xmon, but ptrace
    and the perf_event subsystem can set data breakpoints as well as xmon.
    
    To fix this, we save the host values of the debug registers (CIABR,
    DAWR and DAWRX) before entering the guest and restore them on exit.
    To provide space to save them in the stack frame, we expand the stack
    frame allocated by kvmppc_hv_entry() from 112 to 144 bytes.
    
    Fixes: b005255e ("KVM: PPC: Book3S HV: Context-switch new POWER8 SPRs", 2014-01-08)
    Cc: stable@vger.kernel.org # v3.14+
    Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
    Signed-off-by: default avatarSasha Levin <alexander.levin@verizon.com>
    773853e9
book3s_hv_rmhandlers.S 62.9 KB