From: "Pali Rohár" <pali@kernel.org>
To: Naveen Naidu <naveennaidu479@gmail.com>
Cc: bhelgaas@google.com,
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Subject: Re: [PATCH v3 01/25] PCI: Add PCI_ERROR_RESPONSE and it's related definitions
Date: Thu, 21 Oct 2021 18:08:38 +0200 [thread overview]
Message-ID: <20211021160838.r7t7fmmeseaecfac@pali> (raw)
In-Reply-To: <f7960a4dee0e417eedd7d2e031d04ac9016c6686.1634825082.git.naveennaidu479@gmail.com>
On Thursday 21 October 2021 20:37:26 Naveen Naidu wrote:
> An MMIO read from a PCI device that doesn't exist or doesn't respond
> causes a PCI error. There's no real data to return to satisfy the
> CPU read, so most hardware fabricates ~0 data.
>
> Add a PCI_ERROR_RESPONSE definition for that and use it where
> appropriate to make these checks consistent and easier to find.
>
> Also add helper definitions SET_PCI_ERROR_RESPONSE and
> RESPONSE_IS_PCI_ERROR to make the code more readable.
>
> Suggested-by: Bjorn Helgaas <bhelgaas@google.com>
> Signed-off-by: Naveen Naidu <naveennaidu479@gmail.com>
Reviewed-by: Pali Rohár <pali@kernel.org>
> ---
> include/linux/pci.h | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index cd8aa6fce204..689c8277c584 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -154,6 +154,15 @@ enum pci_interrupt_pin {
> /* The number of legacy PCI INTx interrupts */
> #define PCI_NUM_INTX 4
>
> +/*
> + * Reading from a device that doesn't respond typically returns ~0. A
> + * successful read from a device may also return ~0, so you need additional
> + * information to reliably identify errors.
> + */
> +#define PCI_ERROR_RESPONSE (~0ULL)
> +#define SET_PCI_ERROR_RESPONSE(val) (*(val) = ((typeof(*(val))) PCI_ERROR_RESPONSE))
> +#define RESPONSE_IS_PCI_ERROR(val) ((val) == ((typeof(val)) PCI_ERROR_RESPONSE))
> +
> /*
> * pci_power_t values must match the bits in the Capabilities PME_Support
> * and Control/Status PowerState fields in the Power Management capability.
> --
> 2.25.1
>
next prev parent reply other threads:[~2021-10-21 16:08 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-21 15:07 [PATCH v3 00/25] Unify PCI error response checking Naveen Naidu
2021-10-21 15:07 ` [PATCH v3 01/25] PCI: Add PCI_ERROR_RESPONSE and it's related definitions Naveen Naidu
2021-10-21 16:08 ` Pali Rohár [this message]
2021-11-17 23:58 ` Bjorn Helgaas
2021-11-18 13:30 ` Naveen Naidu
2021-10-21 15:07 ` [PATCH v3 02/25] PCI: Set error response in config access defines when ops->read() fails Naveen Naidu
2021-10-21 15:59 ` Pali Rohár
2021-10-21 15:07 ` [PATCH v3 24/25] PCI: hv: Use PCI_ERROR_RESPONSE to specify hardware read error Naveen Naidu
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