Re: [Qemu-devel] [PATCH v2 3/4] target-ppc: Build error log

[Aravinda Prasad <aravinda@linux.vnet.ibm.com>]

On Friday 05 September 2014 07:44 AM, Alexey Kardashevskiy wrote:
> On 09/04/2014 09:13 PM, Aravinda Prasad wrote:
>> Whenever there is a physical memory error due to bit
>> flips, which cannot be corrected by hardware, the error
>> is passed on to the kernel. If the memory address in
>> error belongs to guest address space then guest kernel
>> is responsible to take action. Hence the error is passed
>> on to guest via KVM by invoking 0x200 NMI vector.
>>
>> However, guest OS, as per PAPR, expects an error log
>> upon such error. This patch registers a new hcall
>> which is issued from 0x200 interrupt vector and builds
>> the error log, copies the error log to rtas space and
>> passes the address of the error log to guest
>>
>> Enhancement to KVM to perform above functionality is
>> already in upstream kernel.
>>
>> Signed-off-by: Aravinda Prasad <aravinda@linux.vnet.ibm.com>
>> ---
>>  hw/ppc/spapr_hcall.c   |  154 ++++++++++++++++++++++++++++++++++++++++++++++++
>>  include/hw/ppc/spapr.h |    4 +
>>  2 files changed, 157 insertions(+), 1 deletion(-)
>>
>> diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
>> index 01650ba..c3aa448 100644
>> --- a/hw/ppc/spapr_hcall.c
>> +++ b/hw/ppc/spapr_hcall.c
>> @@ -14,6 +14,88 @@ struct SPRSyncState {
>>      target_ulong mask;
>>  };
>>  
>> +/* Offset from rtas-base where error log is placed */
>> +#define RTAS_ERROR_OFFSET       (TARGET_PAGE_SIZE)
>> +
>> +#define RTAS_ELOG_SEVERITY_SHIFT         0x5
>> +#define RTAS_ELOG_DISPOSITION_SHIFT      0x3
>> +#define RTAS_ELOG_INITIATOR_SHIFT        0x4
>> +
>> +/*
>> + * Only required RTAS event severity, disposition, initiator
>> + * target and type are copied from arch/powerpc/include/asm/rtas.h
>> + */
>> +
>> +/* RTAS event severity */
>> +#define RTAS_SEVERITY_ERROR_SYNC    0x3
>> +
>> +/* RTAS event disposition */
>> +#define RTAS_DISP_NOT_RECOVERED     0x2
>> +
>> +/* RTAS event initiator */
>> +#define RTAS_INITIATOR_MEMORY       0x4
>> +
>> +/* RTAS event target */
>> +#define RTAS_TARGET_MEMORY          0x4
>> +
>> +/* RTAS event type */
>> +#define RTAS_TYPE_ECC_UNCORR        0x09
>> +
>> +/*
>> + * Currently KVM only passes on the uncorrected machine
>> + * check memory error to guest. Other machine check errors
>> + * such as SLB multi-hit and TLB multi-hit are recovered
>> + * in KVM and are not passed on to guest.
>> + *
>> + * DSISR Bit for uncorrected machine check error. Based
>> + * on arch/powerpc/include/asm/mce.h
>> + */
>> +#define PPC_BIT(bit)                (0x8000000000000000ULL >> bit)
>> +#define P7_DSISR_MC_UE              (PPC_BIT(48))  /* P8 too */
>> +
>> +/* Adopted from kernel source arch/powerpc/include/asm/rtas.h */
>> +struct rtas_error_log {
>> +    /* Byte 0 */
>> +    uint8_t     byte0;          /* Architectural version */
>> +
>> +    /* Byte 1 */
>> +    uint8_t     byte1;
>> +    /* XXXXXXXX
>> +     * XXX      3: Severity level of error
>> +     *    XX    2: Degree of recovery
>> +     *      X   1: Extended log present?
>> +     *       XX 2: Reserved
>> +     */
>> +
>> +    /* Byte 2 */
>> +    uint8_t     byte2;
>> +    /* XXXXXXXX
>> +     * XXXX     4: Initiator of event
>> +     *     XXXX 4: Target of failed operation
>> +     */
>> +    uint8_t     byte3;          /* General event or error*/
>> +};
> 
> 
> Any particular reason not to copy rtas_error_log as is?

No specific reason. I overlooked it when I moved my code form early
prototype version. Will include rest all members.

Regards,
Aravinda


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Regards,
Aravinda