linux-kernel - RE: [PATCH v2 2/8] PCI: Add ACS quirk for Amazon Annapurna Labs root ports

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Message-ID: <DM6PR12MB40103BEB4F4050FBBDCD7C95DACB0@DM6PR12MB4010.namprd12.prod.outlook.com>
Date:   Fri, 19 Jul 2019 08:25:52 +0000
From:   Gustavo Pimentel <Gustavo.Pimentel@...opsys.com>
To:     Jonathan Chocron <jonnyc@...zon.com>,
        "lorenzo.pieralisi@....com" <lorenzo.pieralisi@....com>,
        "bhelgaas@...gle.com" <bhelgaas@...gle.com>,
        "jingoohan1@...il.com" <jingoohan1@...il.com>,
        "gustavo.pimentel@...opsys.com" <Gustavo.Pimentel@...opsys.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "mark.rutland@....com" <mark.rutland@....com>
CC:     "dwmw@...zon.co.uk" <dwmw@...zon.co.uk>,
        "benh@...nel.crashing.org" <benh@...nel.crashing.org>,
        "alisaidi@...zon.com" <alisaidi@...zon.com>,
        "ronenk@...zon.com" <ronenk@...zon.com>,
        "barakw@...zon.com" <barakw@...zon.com>,
        "talel@...zon.com" <talel@...zon.com>,
        "hanochu@...zon.com" <hanochu@...zon.com>,
        "hhhawa@...zon.com" <hhhawa@...zon.com>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: RE: [PATCH v2 2/8] PCI: Add ACS quirk for Amazon Annapurna Labs root
 ports

On Thu, Jul 18, 2019 at 10:45:25, Jonathan Chocron <jonnyc@...zon.com> 
wrote:

> From: Ali Saidi <alisaidi@...zon.com>
> 
> The Amazon's Annapurna Labs root ports don't advertise an ACS
> capability, but they don't allow peer-to-peer transactions and do
> validate bus numbers through the SMMU. Additionally, it's not possible
> for one RP to pass traffic to another RP.
> 
> Signed-off-by: Ali Saidi <alisaidi@...zon.com>
> Signed-off-by: Jonathan Chocron <jonnyc@...zon.com>
> ---
>  drivers/pci/quirks.c | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index 208aacf39329..23672680dba7 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -4366,6 +4366,23 @@ static int pci_quirk_qcom_rp_acs(struct pci_dev *dev, u16 acs_flags)
>  	return ret;
>  }
>  
> +static int pci_quirk_al_acs(struct pci_dev *dev, u16 acs_flags)
> +{
> +	/*
> +	 * Amazon's Annapurna Labs root ports don't include an ACS capability,
> +	 * but do include ACS-like functionality. The hardware doesn't support
> +	 * peer-to-peer transactions via the root port and each has a unique
> +	 * segment number.
> +	 * Additionally, the root ports cannot send traffic to each other.
> +	 */
> +	acs_flags &= ~(PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_SV | PCI_ACS_UF);
> +
> +	if (pci_pcie_type(dev) != PCI_EXP_TYPE_ROOT_PORT)
> +		return -ENOTTY;
> +
> +	return acs_flags ? 0 : 1;
> +}
> +
>  /*
>   * Sunrise Point PCH root ports implement ACS, but unfortunately as shown in
>   * the datasheet (Intel 100 Series Chipset Family PCH Datasheet, Vol. 2,
> @@ -4559,6 +4576,8 @@ static const struct pci_dev_acs_enabled {
>  	{ PCI_VENDOR_ID_AMPERE, 0xE00A, pci_quirk_xgene_acs },
>  	{ PCI_VENDOR_ID_AMPERE, 0xE00B, pci_quirk_xgene_acs },
>  	{ PCI_VENDOR_ID_AMPERE, 0xE00C, pci_quirk_xgene_acs },
> +	/* Amazon Annapurna Labs */
> +	{ PCI_VENDOR_ID_AMAZON_ANNAPURNA_LABS, 0x0031, pci_quirk_al_acs },
>  	{ 0 }
>  };
>  
> -- 
> 2.17.1

Seems ok.

Reviewed-by: Gustavo Pimentel <gustavo.pimentel@...opsys.com>