Re: [PATCH v1] Platform/ARM: Fix platform timer offset in GTDT

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

On 24 April 2018 at 16:19, Sami Mujawar <sami.mujawar@arm.com> wrote:
> The FVP_PLATFORM_TIMER_COUNT is the sum of the memory
> mapped platform timers and the watchdog timers.
>
> The watchdog timers can be disabled by setting the
> FVP_WATCHDOG_COUNT (defined by PcdWatchdogCount)
> to zero.
>
> On the VExpress platform, if the FVP_WATCHDOG_COUNT is
> set to zero, the FVP_PLATFORM_TIMER_COUNT is 1 as
> VExpress has one memory mapped timer.
>
> The code however incorrectly sets the platform timer
> offset to zero in the GTDT. This causes the OS to read
> the platform timer information from an invalid offset,
> and may crash.
>
> Updated the GTDT table to set the platform timer offset
> to zero only when the FVP_PLATFORM_TIMER_COUNT is zero.
>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>
> Reviewed-by: Evan Lloyd <evan.lloyd@arm.com>

Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

Pushed as ed9be80fa9521edc2ef959d493904d4800e64ca1

Thanks

> ---
>
> Notes:
>     v1:
>      - Fix platform timer offset in GTDT for FVP                  [SAMI]
>
>  Platform/ARM/VExpressPkg/AcpiTables/Gtdt.aslc | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/Platform/ARM/VExpressPkg/AcpiTables/Gtdt.aslc b/Platform/ARM/VExpressPkg/AcpiTables/Gtdt.aslc
> index ae570574b298094ff468f30b78fbd8c98db506c5..1cb4b498300cf1a08514835677154eace1dd1803 100644
> --- a/Platform/ARM/VExpressPkg/AcpiTables/Gtdt.aslc
> +++ b/Platform/ARM/VExpressPkg/AcpiTables/Gtdt.aslc
> @@ -108,7 +108,7 @@ FVP_GENERIC_TIMER_DESCRIPTION_TABLES Gtdt = {
>      FVP_GTDT_GTIMER_FLAGS,                                // UINT32  NonSecurePL2TimerFlags
>      FVP_CNT_READ_BASE_ADDRESS,                            // UINT64  CntReadBasePhysicalAddress
>      FVP_PLATFORM_TIMER_COUNT,                             // UINT32  PlatformTimerCount
> -#if (FVP_WATCHDOG_COUNT != 0)
> +#if (FVP_PLATFORM_TIMER_COUNT != 0)
>      sizeof (EFI_ACPI_6_1_GENERIC_TIMER_DESCRIPTION_TABLE) // UINT32  PlatfromTimerOffset
>  #else
>      0
> --
> 'Guid(CE165669-3EF3-493F-B85D-6190EE5B9759)'
>
>