Re: [PATCH v2] UefiCpuPkg/CpuDxe: Fix multiple entries of RT_CODE in memory map

["Wang, Jian J" <jian.j.wang@intel.com>]

Hi Laszlo,

> -----Original Message-----
> From: Laszlo Ersek [mailto:lersek@redhat.com]
> Sent: Wednesday, November 08, 2017 1:14 AM
> To: Wang, Jian J <jian.j.wang@intel.com>; edk2-devel@lists.01.org
> Cc: Yao, Jiewen <jiewen.yao@intel.com>; Dong, Eric <eric.dong@intel.com>
> Subject: Re: [edk2] [PATCH v2] UefiCpuPkg/CpuDxe: Fix multiple entries of
> RT_CODE in memory map
> 
> sorry about the late response
> 
> On 11/03/17 01:57, Jian J Wang wrote:
> >> v2
> >> a. Fix an issue which will cause setting capability failure if size is smaller
> >>    than a page.
> >
> > More than one entry of RT_CODE memory might cause boot problem for
> some
> > old OSs. This patch will fix this issue to keep OS compatibility as much
> > as possible.
> >
> > More detailed information, please refer to
> >     https://bugzilla.tianocore.org/show_bug.cgi?id=753
> >
> > Cc: Eric Dong <eric.dong@intel.com>
> > Cc: Jiewen Yao <jiewen.yao@intel.com>
> > Cc: Laszlo Ersek <lersek@redhat.com>
> > Contributed-under: TianoCore Contribution Agreement 1.1
> > Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
> > ---
> >  UefiCpuPkg/CpuDxe/CpuPageTable.c | 18 ++++++++++++++----
> >  1 file changed, 14 insertions(+), 4 deletions(-)
> >
> > diff --git a/UefiCpuPkg/CpuDxe/CpuPageTable.c
> b/UefiCpuPkg/CpuDxe/CpuPageTable.c
> > index d312eb66f8..4a7827ebc9 100644
> > --- a/UefiCpuPkg/CpuDxe/CpuPageTable.c
> > +++ b/UefiCpuPkg/CpuDxe/CpuPageTable.c
> > @@ -809,7 +809,9 @@ RefreshGcdMemoryAttributesFromPaging (
> >    PageLength    = 0;
> >
> >    for (Index = 0; Index < NumberOfDescriptors; Index++) {
> > -    if (MemorySpaceMap[Index].GcdMemoryType ==
> EfiGcdMemoryTypeNonExistent) {
> > +    if (MemorySpaceMap[Index].GcdMemoryType ==
> EfiGcdMemoryTypeNonExistent
> > +        || (MemorySpaceMap[Index].BaseAddress & EFI_PAGE_MASK) != 0
> > +        || (MemorySpaceMap[Index].Length & EFI_PAGE_MASK) != 0) {
> >        continue;
> >      }
> 
> When exactly do the new conditions match?
> 
> I thought the base addresses and the lengths in the GCD memory space map
> are all page aligned. Is that not the case?
> 
> If these conditions are just a sanity check (i.e. we never expect them
> to fire), then should we perpahs turn them into ASSERT()s?
> 

I found that there's a mmio entry in memory map on OVMF which has size
less than a page. I didn't encounter this before. Maybe some recent changes
in other part of EDKII caused this situation. So ASSERT is not enough.

> >
> > @@ -829,6 +831,15 @@ RefreshGcdMemoryAttributesFromPaging (
> >      // Sync real page attributes to GCD
> >      BaseAddress       = MemorySpaceMap[Index].BaseAddress;
> >      MemorySpaceLength = MemorySpaceMap[Index].Length;
> > +    Capabilities      = MemorySpaceMap[Index].Capabilities |
> > +                        EFI_MEMORY_PAGETYPE_MASK;
> > +    Status = gDS->SetMemorySpaceCapabilities (
> > +                    BaseAddress,
> > +                    MemorySpaceLength,
> > +                    Capabilities
> > +                    );
> > +    ASSERT_EFI_ERROR (Status);
> > +
> 
> OK, so I guess we simply add EFI_MEMORY_PAGETYPE_MASK to the
> capabilities of all memory space map entries that have a type different
> from non-existent. We discussed it before and (apparently) it is
> considered safe.
> 

Yes. I've validated different OSs boot. It's safe to stay this way.

> >      while (MemorySpaceLength > 0) {
> >        if (PageLength == 0) {
> >          PageEntry = GetPageTableEntry (&PagingContext, BaseAddress,
> &PageAttribute);
> > @@ -846,7 +857,6 @@ RefreshGcdMemoryAttributesFromPaging (
> >          if (Attributes != (MemorySpaceMap[Index].Attributes &
> EFI_MEMORY_PAGETYPE_MASK)) {
> >            DoUpdate = TRUE;
> >            Attributes |= (MemorySpaceMap[Index].Attributes &
> ~EFI_MEMORY_PAGETYPE_MASK);
> > -          Capabilities = Attributes | MemorySpaceMap[Index].Capabilities;
> >          } else {
> >            DoUpdate = FALSE;
> >          }
> > @@ -854,8 +864,8 @@ RefreshGcdMemoryAttributesFromPaging (
> >
> >        Length = MIN (PageLength, MemorySpaceLength);
> >        if (DoUpdate) {
> > -        gDS->SetMemorySpaceCapabilities (BaseAddress, Length, Capabilities);
> > -        gDS->SetMemorySpaceAttributes (BaseAddress, Length, Attributes);
> > +        Status = gDS->SetMemorySpaceAttributes (BaseAddress, Length,
> Attributes);
> > +        ASSERT_EFI_ERROR (Status);
> >          DEBUG ((DEBUG_INFO, "Update memory space attribute: [%02d] %016lx
> - %016lx (%08lx -> %08lx)\r\n",
> >                               Index, BaseAddress, BaseAddress + Length - 1,
> >                               MemorySpaceMap[Index].Attributes, Attributes));
> >
> 
> I'll let you decide about the EFI_PAGE_MASK conditions near the top.
> 
> Acked-by: Laszlo Ersek <lersek@redhat.com>
> 

Thanks.

> Thanks
> Laszlo