linux-kernel - Re: [PATCH v7 0/2] PCI: quirks: Cavium ThunderX ACS quirk update

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Message-ID: <20171019115921.GA6199@localhost.localdomain>
Date:   Thu, 19 Oct 2017 04:59:21 -0700
From:   Vadim Lomovtsev <Vadim.Lomovtsev@...iumnetworks.com>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     bhelgaas@...gle.com, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org, alex.williamson@...hat.com,
        Wilson.Snyder@...ium.com, robert.richter@...ium.com,
        david.daney@...ium.com, mjaggi@...iumnetworks.com,
        Vadim Lomovtsev <Vadim.Lomovtsev@...ium.com>
Subject: Re: [PATCH v7 0/2] PCI: quirks: Cavium ThunderX ACS quirk update

On Thu, Oct 19, 2017 at 06:26:45AM -0500, Bjorn Helgaas wrote:
> On Tue, Oct 17, 2017 at 05:47:37AM -0700, Vadim Lomovtsev wrote:
> > From: Vadim Lomovtsev <Vadim.Lomovtsev@...ium.com>
> > 
> > version 7:
> > - update patch description accordingly to review comments;
> > - split for two patches: for ACS mask change and device id match change;
> > - remove macro #define of ACS flags, put it back to quirk function;
> > - remove '__inline_' from device id matching function;
> > - wrap code comments to fit into 80 columns;
> > - comment fix: change 0xa00 to 0xf800 for matching function description;
> > 
> > version 6:
> > - comment typo fix: change 0xa00 to 0xa000;
> > 
> > version 5:
> > - update code comments accordingly to review comments;
> > 
> > version 4:
> > - update ACS mask (remove TB and TD bits), update commit message (remove
> >   ACS register printout);
> > 
> > version 3:
> > - update subject: remove CN8XXX from subject line, replace it with ThunderX;
> > 
> > version 2:
> > - update match function in order to filter only ThunderX devices by device
> >   ids to properly filter CN8XXX devices, update subject & description with
> >   ACS register info (v2 was rejected by maillist due to triple X in subject);
> >   
> > Vadim Lomovtsev (2):
> >   PCI: quirks: Set Cavium ACS capability quirk flags to assert
> >     RR/CR/SV/UF.
> >   PCI: quirks: Apply Cavium ThunderX ACS quirk only to Root Ports
> > 
> >  drivers/pci/quirks.c | 26 ++++++++++++++++++++------
> >  1 file changed, 20 insertions(+), 6 deletions(-)
> 
> If I'm reading this correctly, the first patch is basically fixing a bug in
> the original Cavium ACS quirk (b404bcfbf035 ("PCI: Add ACS quirk for all
> Cavium devices")).  Right?

Yes, first patch fixes improper ACS flags in the patch you mentioned.

The second one fixes devid check from another patch
(b77d537d00d0 PCI: Apply Cavium ACS quirk only to CN81xx/CN83xx/CN88xx devices).

> 
> I put them on pci/virtualization for v4.15 as follows (patches unchanged,
> changelogs wordsmithed).
>

Good, thank you.

> You mentioned stable backports.  b404bcfbf035 ("PCI: Add ACS quirk for all
> Cavium devices") appeared in v4.6.  b77d537d00d0 ("PCI: Apply Cavium ACS
> quirk only to CN81xx/CN83xx/CN88xx devices") appeared in v4.12.  I assume
> you would ideally want all this backported as far as v4.6?  We'd have to
> figure out how to express that in stable tags.

Ideally yes, I think we would need to have them backported onto stable(s),
but so far I didn't see any bug-reports which could require these fixes.

Anyway, in term of backporting them - are there anything I can help with ?

WBR,
Vadim

> 
> 
> commit 60f6d5f7ebc4bba83d73115f58b805f2f2618667
> Author: Vadim Lomovtsev <Vadim.Lomovtsev@...ium.com>
> Date:   Tue Oct 17 05:47:38 2017 -0700
> 
>     PCI: Set Cavium ACS capability quirk flags to assert RR/CR/SV/UF
>     
>     The Cavium ThunderX (CN8XXX) family of PCIe Root Ports does not advertise
>     an ACS capability.  However, the RTL internally implements similar
>     protection as if ACS had Request Redirection, Completion Redirection,
>     Source Validation, and Upstream Forwarding features enabled.
>     
>     Change Cavium ACS capabilities quirk flags accordingly.
>     
>     Fixes: b404bcfbf035 ("PCI: Add ACS quirk for all Cavium devices")
>     Signed-off-by: Vadim Lomovtsev <Vadim.Lomovtsev@...ium.com>
>     Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
> 
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index a4d33619a7bb..c23650cfd5a1 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -4214,12 +4214,14 @@ static int pci_quirk_amd_sb_acs(struct pci_dev *dev, u16 acs_flags)
>  static int pci_quirk_cavium_acs(struct pci_dev *dev, u16 acs_flags)
>  {
>  	/*
> -	 * Cavium devices matching this quirk do not perform peer-to-peer
> -	 * with other functions, allowing masking out these bits as if they
> -	 * were unimplemented in the ACS capability.
> +	 * Cavium root ports don't advertise an ACS capability.  However,
> +	 * the RTL internally implements similar protection as if ACS had
> +	 * Request Redirection, Completion Redirection, Source Validation,
> +	 * and Upstream Forwarding features enabled.  Assert that the
> +	 * hardware implements and enables equivalent ACS functionality for
> +	 * these flags.
>  	 */
> -	acs_flags &= ~(PCI_ACS_SV | PCI_ACS_TB | PCI_ACS_RR |
> -		       PCI_ACS_CR | PCI_ACS_UF | PCI_ACS_DT);
> +	acs_flags &= ~(PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_SV | PCI_ACS_UF);
>  
>  	if (!((dev->device >= 0xa000) && (dev->device <= 0xa0ff)))
>  		return -ENOTTY;
> 
> commit 35da518fcad24f7be515976238a4667b5ccd1711
> Author: Vadim Lomovtsev <Vadim.Lomovtsev@...ium.com>
> Date:   Tue Oct 17 05:47:39 2017 -0700
> 
>     PCI: Apply Cavium ThunderX ACS quirk to more Root Ports
>     
>     Extend the Cavium ThunderX ACS quirk to cover more device IDs and restrict
>     it to only Root Ports.
>     
>     Signed-off-by: Vadim Lomovtsev <Vadim.Lomovtsev@...ium.com>
>     [bhelgaas: changelog]
>     Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
> 
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index c23650cfd5a1..0e22cce05742 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -4211,6 +4211,19 @@ static int pci_quirk_amd_sb_acs(struct pci_dev *dev, u16 acs_flags)
>  #endif
>  }
>  
> +static bool pci_quirk_cavium_acs_match(struct pci_dev *dev)
> +{
> +	/*
> +	 * Effectively selects all downstream ports for whole ThunderX 1
> +	 * family by 0xf800 mask (which represents 8 SoCs), while the lower
> +	 * bits of device ID are used to indicate which subdevice is used
> +	 * within the SoC.
> +	 */
> +	return (pci_is_pcie(dev) &&
> +		(pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT) &&
> +		((dev->device & 0xf800) == 0xa000));
> +}
> +
>  static int pci_quirk_cavium_acs(struct pci_dev *dev, u16 acs_flags)
>  {
>  	/*
> @@ -4223,7 +4236,7 @@ static int pci_quirk_cavium_acs(struct pci_dev *dev, u16 acs_flags)
>  	 */
>  	acs_flags &= ~(PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_SV | PCI_ACS_UF);
>  
> -	if (!((dev->device >= 0xa000) && (dev->device <= 0xa0ff)))
> +	if (!pci_quirk_cavium_acs_match(dev))
>  		return -ENOTTY;
>  
>  	return acs_flags ? 0 : 1;