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

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Message-ID: <20241024160625.GC965@yaz-khff2.amd.com>
Date: Thu, 24 Oct 2024 12:06:25 -0400
From: Yazen Ghannam <yazen.ghannam@....com>
To: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.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, 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?

Thanks,
Yazen