linux-kernel - Re: [PATCH 14/16] x86/amd_smn, platform/x86/amd/hsmp: Have HSMP use SMN

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Message-ID: <d44f45c1-a550-de07-d1fa-91dfe0adb47f@linux.intel.com>
Date: Fri, 25 Oct 2024 16:39:21 +0300 (EEST)
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: Yazen Ghannam <yazen.ghannam@....com>
cc: linux-edac@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>, 
    tony.luck@...el.com, x86@...nel.org, avadhut.naik@....com, 
    john.allen@....com, mario.limonciello@....com, bhelgaas@...gle.com, 
    Shyam-sundar.S-k@....com, richard.gong@....com, jdelvare@...e.com, 
    linux@...ck-us.net, clemens@...isch.de, 
    Hans de Goede <hdegoede@...hat.com>, linux-pci@...r.kernel.org, 
    linux-hwmon@...r.kernel.org, platform-driver-x86@...r.kernel.org, 
    naveenkrishna.chatradhi@....com, carlos.bilbao.osdev@...il.com
Subject: Re: [PATCH 14/16] x86/amd_smn, platform/x86/amd/hsmp: Have HSMP use
 SMN

On Thu, 24 Oct 2024, Yazen Ghannam wrote:

> On Thu, Oct 24, 2024 at 04:23:55PM +0300, Ilpo Järvinen wrote:
> > On Wed, 23 Oct 2024, Yazen Ghannam wrote:
> > 
> > > The HSMP interface is just an SMN interface with different offsets.
> > > 
> > > Define an HSMP wrapper in the SMN code and have the HSMP platform driver
> > > use that rather than a local solution.
> > > 
> > > Also, remove the "root" member from AMD_NB, since there are no more
> > > users of it.
> > > 
> > > Signed-off-by: Yazen Ghannam <yazen.ghannam@....com>
> > > ---
> > >  arch/x86/include/asm/amd_nb.h    |  1 -
> > >  arch/x86/include/asm/amd_smn.h   |  3 +++
> > >  arch/x86/kernel/amd_nb.c         |  1 -
> > >  arch/x86/kernel/amd_smn.c        |  9 +++++++++
> > >  drivers/platform/x86/amd/Kconfig |  2 +-
> > >  drivers/platform/x86/amd/hsmp.c  | 32 +++++---------------------------
> > >  6 files changed, 18 insertions(+), 30 deletions(-)
> > > 
> > > diff --git a/arch/x86/include/asm/amd_nb.h b/arch/x86/include/asm/amd_nb.h
> > > index 55c03d3495bc..cbe31e316e39 100644
> > > --- a/arch/x86/include/asm/amd_nb.h
> > > +++ b/arch/x86/include/asm/amd_nb.h
> > > @@ -27,7 +27,6 @@ struct amd_l3_cache {
> > >  };
> > >  
> > >  struct amd_northbridge {
> > > -	struct pci_dev *root;
> > >  	struct pci_dev *misc;
> > >  	struct pci_dev *link;
> > >  	struct amd_l3_cache l3_cache;
> > > diff --git a/arch/x86/include/asm/amd_smn.h b/arch/x86/include/asm/amd_smn.h
> > > index 6850de69f863..f0eb12859c42 100644
> > > --- a/arch/x86/include/asm/amd_smn.h
> > > +++ b/arch/x86/include/asm/amd_smn.h
> > > @@ -8,4 +8,7 @@
> > >  int __must_check amd_smn_read(u16 node, u32 address, u32 *value);
> > >  int __must_check amd_smn_write(u16 node, u32 address, u32 value);
> > >  
> > > +/* Should only be used by the HSMP driver. */
> > > +int __must_check amd_smn_hsmp_rdwr(u16 node, u32 address, u32 *value, bool write);
> > > +
> > >  #endif /* _ASM_X86_AMD_SMN_H */
> > > diff --git a/arch/x86/kernel/amd_nb.c b/arch/x86/kernel/amd_nb.c
> > > index 10cdeddeda02..4c22317a6dfe 100644
> > > --- a/arch/x86/kernel/amd_nb.c
> > > +++ b/arch/x86/kernel/amd_nb.c
> > > @@ -73,7 +73,6 @@ static int amd_cache_northbridges(void)
> > >  	amd_northbridges.nb = nb;
> > >  
> > >  	for (i = 0; i < amd_northbridges.num; i++) {
> > > -		node_to_amd_nb(i)->root = amd_node_get_root(i);
> > >  		node_to_amd_nb(i)->misc = amd_node_get_func(i, 3);
> > >  		node_to_amd_nb(i)->link = amd_node_get_func(i, 4);
> > >  	}
> > > diff --git a/arch/x86/kernel/amd_smn.c b/arch/x86/kernel/amd_smn.c
> > > index 997fd3edd9c0..527dda8e3a2b 100644
> > > --- a/arch/x86/kernel/amd_smn.c
> > > +++ b/arch/x86/kernel/amd_smn.c
> > > @@ -18,6 +18,9 @@ static DEFINE_MUTEX(smn_mutex);
> > >  #define SMN_INDEX_OFFSET	0x60
> > >  #define SMN_DATA_OFFSET		0x64
> > >  
> > > +#define HSMP_INDEX_OFFSET	0xc4
> > > +#define HSMP_DATA_OFFSET	0xc8
> > > +
> > >  /*
> > >   * SMN accesses may fail in ways that are difficult to detect here in the called
> > >   * functions amd_smn_read() and amd_smn_write(). Therefore, callers must do
> > > @@ -100,6 +103,12 @@ int __must_check amd_smn_write(u16 node, u32 address, u32 value)
> > >  }
> > >  EXPORT_SYMBOL_GPL(amd_smn_write);
> > >  
> > > +int __must_check amd_smn_hsmp_rdwr(u16 node, u32 address, u32 *value, bool write)
> > > +{
> > > +	return __amd_smn_rw(HSMP_INDEX_OFFSET, HSMP_DATA_OFFSET, node, address, value, write);
> > > +}
> > > +EXPORT_SYMBOL_GPL(amd_smn_hsmp_rdwr);
> > > +
> > >  static int amd_cache_roots(void)
> > >  {
> > >  	u16 node, num_nodes = amd_num_nodes();
> > > diff --git a/drivers/platform/x86/amd/Kconfig b/drivers/platform/x86/amd/Kconfig
> > > index f88682d36447..e100b315c62b 100644
> > > --- a/drivers/platform/x86/amd/Kconfig
> > > +++ b/drivers/platform/x86/amd/Kconfig
> > > @@ -8,7 +8,7 @@ source "drivers/platform/x86/amd/pmc/Kconfig"
> > >  
> > >  config AMD_HSMP
> > >  	tristate "AMD HSMP Driver"
> > > -	depends on AMD_NB && X86_64 && ACPI
> > > +	depends on AMD_SMN && X86_64 && ACPI
> > >  	help
> > >  	  The driver provides a way for user space tools to monitor and manage
> > >  	  system management functionality on EPYC server CPUs from AMD.
> > > diff --git a/drivers/platform/x86/amd/hsmp.c b/drivers/platform/x86/amd/hsmp.c
> > > index 8fcf38eed7f0..544efb0255c0 100644
> > > --- a/drivers/platform/x86/amd/hsmp.c
> > > +++ b/drivers/platform/x86/amd/hsmp.c
> > 
> > FYI, there has been major restructuring done for this driver in 
> > pdx86/for-next.
> >
> 
> Yep, no problem. I can rebase these changes on top of those.
> 
> Any comments on the general approach?

I deemed looking deeper into the patch waste of my time due to the 
expected changes, so no comments at this time.

-- 
 i.