[Skiboot] [PATCH] phb4: Enforce root complex config space size of 2048

[Michael Neuling]

On Fri, 2017-05-05 at 18:05 +0200, Benjamin Herrenschmidt wrote:
> On Fri, 2017-05-05 at 16:51 +1000, Michael Neuling wrote:
> > The root complex config space size on PHB4 is 2048. This patch sets
> > that size and enforces it when trying to read/write the config space
> > in the root complex.
> > 
> > Without this someone reading the config space via /sysfs in linux will
> > cause an EEH on the PHB.
> > 
> > Signed-off-by: Michael Neuling <mikey at neuling.org>
> 
> Acked-by: Benjamin Herrenschmidt <benh at kernel.crashing.org>

Stewart, benh and I talked off offline about this and decided to return 0xff
rather than this error.

So hold off on taking this taking this until I repost.

Mikey

> 
> > ---
> >  hw/phb4.c           | 6 ++++++
> >  include/phb4-regs.h | 1 +
> >  2 files changed, 7 insertions(+)
> > 
> > diff --git a/hw/phb4.c b/hw/phb4.c
> > index 49d4a0f4c9..28bf6f75d7 100644
> > --- a/hw/phb4.c
> > +++ b/hw/phb4.c
> > @@ -208,6 +208,9 @@ static int64_t phb4_rc_read(struct phb4 *p, uint32_t
> > offset, uint8_t sz,
> >  	uint32_t reg = offset & ~3;
> >  	uint32_t oval;
> >  
> > +	if (reg >= PHB_RC_CONFIG_SIZE)
> > +		return OPAL_PARAMETER;
> > +
> >  	/* Some registers are handled locally */
> >  	switch (reg) {
> >  		/* Bridge base/limit registers are cached here as HW
> > @@ -257,6 +260,9 @@ static int64_t phb4_rc_write(struct phb4 *p, uint32_t
> > offset, uint8_t sz,
> >  	uint32_t old, mask, shift;
> >  	int64_t rc;
> >  
> > +	if (reg > PHB_RC_CONFIG_SIZE)
> > +		return OPAL_PARAMETER;
> > +
> >  	/* If size isn't 4-bytes, do a RMW cycle
> >  	 *
> >  	 * XXX TODO: Filter out registers that do write-1-to-clear !!!
> > diff --git a/include/phb4-regs.h b/include/phb4-regs.h
> > index 548094907a..92bee88f6b 100644
> > --- a/include/phb4-regs.h
> > +++ b/include/phb4-regs.h
> > @@ -235,6 +235,7 @@
> >  
> >  // FIXME add more here
> >  #define PHB_RC_CONFIG_BASE			0x1000
> > +#define   PHB_RC_CONFIG_SIZE			0x800
> >  
> >  /* PHB4 REGB registers */
> >  #define PHB_PBL_CONTROL				0x1800
> 
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