Re: [Qemu-arm] [PATCH v15 10/10] target-arm: kvm64: handle SIGBUS signal from kernel or KVM

[Peter Maydell]

On Thu, 8 Nov 2018 at 10:18, Dongjiu Geng <address@hidden> wrote:
>
> Add SIGBUS signal handler. In this handler, it checks the SIGBUS type,
> translates the host VA delivered by host to guest PA, then fill this PA
> to guest APEI GHES memory, then notify guest according to the SIGBUS type.
> There are two kinds of SIGBUS that QEMU needs to handle, which are
> BUS_MCEERR_AO and BUS_MCEERR_AR.

> +bool ghes_record_errors(uint32_t notify, uint64_t physical_address)
> +{
> +    uint64_t error_block_addr, read_ack_register_addr;
> +    int read_ack_register = 0, loop = 0;
> +    uint64_t start_addr = le32_to_cpu(ges.ghes_addr_le);
> +    bool ret = GHES_CPER_FAIL;
> +    const uint8_t error_source_id[] = { 0xff, 0xff, 0xff, 0xff,
> +                                        0xff, 0xff, 0xff, 0, 1};
> +
> +    /*
> +     * | +---------------------+ ges.ghes_addr_le
> +     * | |error_block_address0|
> +     * | +---------------------+
> +     * | |error_block_address1|
> +     * | +---------------------+ --+--
> +     * | |    .............    | GHES_ADDRESS_SIZE
> +     * | +---------------------+ --+--
> +     * | |error_block_addressN|
> +     * | +---------------------+
> +     * | | read_ack_register0  |
> +     * | +---------------------+ --+--
> +     * | | read_ack_register1  | GHES_ADDRESS_SIZE
> +     * | +---------------------+ --+--
> +     * | |   .............     |
> +     * | +---------------------+
> +     * | | read_ack_registerN  |
> +     * | +---------------------+ --+--
> +     * | |      CPER           |   |
> +     * | |      ....           | GHES_MAX_RAW_DATA_LENGT
> +     * | |      CPER           |   |
> +     * | +---------------------+ --+--
> +     * | |    ..........       |
> +     * | +---------------------+
> +     * | |      CPER           |
> +     * | |      ....           |
> +     * | |      CPER           |
> +     * | +---------------------+
> +     */
> +    if (physical_address && notify < ACPI_HEST_NOTIFY_RESERVED) {

Why is a zero physical address special here? Shouldn't we be
able to report "the memory backing physaddr 0 has a fault" ?

thanks
-- PMM