On Thu, May 21, 2020 at 02:03:36PM +0100, Peter Maydell wrote:
> On Thu, 14 May 2020 at 15:22, Peter Maydell <peter.mayd...@linaro.org> wrote:
> >
> > From: Dongjiu Geng <gengdong...@huawei.com>
> >
> > kvm_arch_on_sigbus_vcpu() error injection uses source_id as
> > index in etc/hardware_errors to find out Error Status Data
> > Block entry corresponding to error source. So supported source_id
> > values should be assigned here and not be changed afterwards to
> > make sure that guest will write error into expected Error Status
> > Data Block.
> >
> > Before QEMU writes a new error to ACPI table, it will check whether
> > previous error has been acknowledged. If not acknowledged, the new
> > errors will be ignored and not be recorded. For the errors section
> > type, QEMU simulate it to memory section error.
>
> Hi; Coverity points out (CID 1428962) that there is
> unreachable code in this function:
>
> > +static int acpi_ghes_record_mem_error(uint64_t error_block_address,
> > + uint64_t error_physical_addr)
> > +{
> > + GArray *block;
> > +
> > + /* Memory Error Section Type */
> > + const uint8_t uefi_cper_mem_sec[] =
> > + UUID_LE(0xA5BC1114, 0x6F64, 0x4EDE, 0xB8, 0x63, 0x3E, 0x83, \
> > + 0xED, 0x7C, 0x83, 0xB1);
> > +
> > + /* invalid fru id: ACPI 4.0: 17.3.2.6.1 Generic Error Data,
> > + * Table 17-13 Generic Error Data Entry
> > + */
> > + QemuUUID fru_id = {};
> > + uint32_t data_length;
> > +
> > + block = g_array_new(false, true /* clear */, 1);
> > +
> > + /* This is the length if adding a new generic error data entry*/
> > + data_length = ACPI_GHES_DATA_LENGTH + ACPI_GHES_MEM_CPER_LENGTH;
>
> Here data_length has a constant value...
>
> > +
> > + /*
> > + * Check whether it will run out of the preallocated memory if adding
> > a new
> > + * generic error data entry
> > + */
> > + if ((data_length + ACPI_GHES_GESB_SIZE) >
> > ACPI_GHES_MAX_RAW_DATA_LENGTH) {
>
> ...but here we immediately have a runtime check which can't possibly
> fail because of the values of the constants involved, so this
> if() block is dead code.
>
> > + error_report("Not enough memory to record new CPER!!!");
> > + g_array_free(block, true);
> > + return -1;
> > + }
>
> What was this code trying to do? Is the initial value of
> data_length incorrect, or is the if() condition wrong, or
> should this simply have been an assert() ?
>
> thanks
> -- PMM
It's just a validity check. assert will do just as well.
--
MST
