On 21.08.2012, at 15:51, Bharat Bhushan wrote:
> This patch defines the interface parameter for KVM_SET_GUEST_DEBUG
> ioctl support. Follow up patches will use this for setting up
> hardware breakpoints, watchpoints and software breakpoints.
>
> Signed-off-by: Bharat Bhushan <bharat.bhushan@xxxxxxxxxxxxx>
> ---
> arch/powerpc/include/asm/kvm.h | 33 +++++++++++++++++++++++++++++++++
> arch/powerpc/kvm/book3s.c | 6 ++++++
> arch/powerpc/kvm/booke.c | 6 ++++++
> arch/powerpc/kvm/powerpc.c | 6 ------
> 4 files changed, 45 insertions(+), 6 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/kvm.h b/arch/powerpc/include/asm/kvm.h
> index 3c14202..61b197e 100644
> --- a/arch/powerpc/include/asm/kvm.h
> +++ b/arch/powerpc/include/asm/kvm.h
> @@ -269,8 +269,41 @@ struct kvm_debug_exit_arch {
>
> /* for KVM_SET_GUEST_DEBUG */
> struct kvm_guest_debug_arch {
> + struct {
> + /* H/W breakpoint/watchpoint address */
> + __u64 addr;
> + /*
> + * Type denotes h/w breakpoint, read watchpoint, write
> + * watchpoint or watchpoint (both read and write).
> + */
> +#define KVMPPC_DEBUG_NOTYPE 0x0
> +#define KVMPPC_DEBUG_BREAKPOINT (1UL << 1)
> +#define KVMPPC_DEBUG_WATCH_WRITE (1UL << 2)
> +#define KVMPPC_DEBUG_WATCH_READ (1UL << 3)
> + __u32 type;
> + __u32 pad1;
Why the padding?
> + __u64 pad2;
> + } bp[16];
Why 16?
> };
>
> +/* Debug related defines */
> +/*
> + * kvm_guest_debug->control is a 32 bit field. The lower 16 bits are generic
> + * and upper 16 bits are architecture specific. Architecture specific defines
> + * that ioctl is for setting hardware breakpoint or software breakpoint.
> + */
> +#define KVM_GUESTDBG_USE_SW_BP 0x00010000
> +#define KVM_GUESTDBG_USE_HW_BP 0x00020000
> +
> +/* When setting software breakpoint, Change the software breakpoint
> + * instruction to special trap instruction and set KVM_GUESTDBG_USE_SW_BP
> + * flag in kvm_guest_debug->control. KVM does keep track of software
> + * breakpoints. So when KVM_GUESTDBG_USE_SW_BP flag is set and special trap
> + * instruction is executed by guest then exit to userspace.
> + * NOTE: A Nice interface can be added to get the special trap instruction.
> + */
> +#define KVMPPC_INST_GUEST_GDB 0x7C00021C /* ehpriv OC=0 */
This definitely has to be passed to user space (which writes that instruction into guest phys memory). Other PPC subarchs will use different instructions. Just model it as a read-only ONE_REG.
Alex
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