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KVM: PPC: BOOKE: Emulate debug registers and exception

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This patch emulates debug registers and debug exception
to support guest using debug resource. This enables running
gdb/kgdb etc in guest.

On BOOKE architecture we cannot share debug resources between QEMU and
guest because:
    When QEMU is using debug resources then debug exception must
    be always enabled. To achieve this we set MSR_DE and also set
    MSRP_DEP so guest cannot change MSR_DE.

    When emulating debug resource for guest we want guest
    to control MSR_DE (enable/disable debug interrupt on need).

    So above mentioned two configuration cannot be supported
    at the same time. So the result is that we cannot share
    debug resources between QEMU and Guest on BOOKE architecture.

In the current design QEMU gets priority over guest, this means that if
QEMU is using debug resources then guest cannot use them and if guest is
using debug resource then QEMU can overwrite them.

Signed-off-by: Bharat Bhushan <Bharat.Bhushan@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
This commit is contained in:
Bharat Bhushan
2014-08-13 14:39:44 +05:30
committed by Alexander Graf
parent 3840edc803
commit 2f699a59f3
4 changed files with 194 additions and 1 deletions
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2
arch/powerpc/include/asm/reg_booke.h
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@@ -319,6 +319,8 @@
* DBSR bits which have conflicting definitions on true Book E versus IBM 40x.
*/
#ifdef CONFIG_BOOKE
#define DBSR_IDE 0x80000000 /* Imprecise Debug Event */
#define DBSR_MRR 0x30000000 /* Most Recent Reset */
#define DBSR_IC 0x08000000 /* Instruction Completion */
#define DBSR_BT 0x04000000 /* Branch Taken */
#define DBSR_IRPT 0x02000000 /* Exception Debug Event */