[PATCH] lib: sbi: Fix GPA passed to __sbi_hfence_gvma_xyz() functions

[Anup Patel]

On Tue, Oct 26, 2021 at 5:49 PM Xiang W <wxjstz at 126.com> wrote:
>
> 在 2021-10-26星期二的 17:18 +0530，Anup Patel写道：
> > The parameter passed to HFENCE.GVMA instruction in rs1 register
> > is guest physical address right shifted by 2 (i.e. divided by 4).
> >
> > Unfortunately, we overlooked the semantics of rs1 registers for
> > HFENCE.GVMA instruction and never right shifted guest physical
> > address by 2. This issue did not manifest for hypervisors till
> > now because all H-extension implementations (such as QEMU, Spike,
> > Rocket Core FPGA, etc) we tried till now were conservatively
> > flushing everything upon any HFENCE.GVMA instruction.
> >
> > This patch fixes GPA passed to __sbi_hfence_gvma_vmid_gpa()
> > and __sbi_hfence_gvma_gpa() functions.
> >
> > Fixes: 331ff6a162c1 ("lib: Support stage1 and stage2 tlb flushing")
> > Reported-by: Ian Huang <ihuang at ventanamicro.com>
> > Signed-off-by: Anup Patel <anup.patel at wdc.com>
> We can keep the api unchanged and add a shift instruction in
> __sbi_hfence_gvma_vmid_gpa/__sbi_hfence_gvma_gpa

That's not a good idea because __sbi_hfence_xyz() functions are
substitute for missing H-extension support in GCC assembler.

In future these __sbi_hfence_xyz() will be replaced with inline
assembly but we will have to specify minimum required GCC
and LLVM versions for compiling OpenSBI.

Regards,
Anup

>
> srli    a0,a0,2
>
> Regards,
> Xiang W
> > ---
> >  include/sbi/sbi_hfence.h | 5 +++--
> >  lib/sbi/sbi_hfence.S     | 4 ++--
> >  lib/sbi/sbi_tlb.c        | 4 ++--
> >  3 files changed, 7 insertions(+), 6 deletions(-)
> >
> > diff --git a/include/sbi/sbi_hfence.h b/include/sbi/sbi_hfence.h
> > index 4420f27..d3958f1 100644
> > --- a/include/sbi/sbi_hfence.h
> > +++ b/include/sbi/sbi_hfence.h
> > @@ -12,13 +12,14 @@
> >  #define __SBI_FENCE_H__
> >
> >  /** Invalidate Stage2 TLBs for given VMID and guest physical address
> > */
> > -void __sbi_hfence_gvma_vmid_gpa(unsigned long gpa, unsigned long
> > vmid);
> > +void __sbi_hfence_gvma_vmid_gpa(unsigned long gpa_divby_4,
> > +                               unsigned long vmid);
> >
> >  /** Invalidate Stage2 TLBs for given VMID */
> >  void __sbi_hfence_gvma_vmid(unsigned long vmid);
> >
> >  /** Invalidate Stage2 TLBs for given guest physical address */
> > -void __sbi_hfence_gvma_gpa(unsigned long gpa);
> > +void __sbi_hfence_gvma_gpa(unsigned long gpa_divby_4);
> >
> >  /** Invalidate all possible Stage2 TLBs */
> >  void __sbi_hfence_gvma_all(void);
> > diff --git a/lib/sbi/sbi_hfence.S b/lib/sbi/sbi_hfence.S
> > index d05becb..e11e650 100644
> > --- a/lib/sbi/sbi_hfence.S
> > +++ b/lib/sbi/sbi_hfence.S
> > @@ -27,7 +27,7 @@
> >         .global __sbi_hfence_gvma_vmid_gpa
> >  __sbi_hfence_gvma_vmid_gpa:
> >         /*
> > -        * rs1 = a0 (GPA)
> > +        * rs1 = a0 (GPA >> 2)
> >          * rs2 = a1 (VMID)
> >          * HFENCE.GVMA a0, a1
> >          * 0110001 01011 01010 000 00000 1110011
> > @@ -51,7 +51,7 @@ __sbi_hfence_gvma_vmid:
> >         .global __sbi_hfence_gvma_gpa
> >  __sbi_hfence_gvma_gpa:
> >         /*
> > -        * rs1 = a0 (GPA)
> > +        * rs1 = a0 (GPA >> 2)
> >          * rs2 = zero
> >          * HFENCE.GVMA a0
> >          * 0110001 00000 01010 000 00000 1110011
> > diff --git a/lib/sbi/sbi_tlb.c b/lib/sbi/sbi_tlb.c
> > index efa74a7..4c142ea 100644
> > --- a/lib/sbi/sbi_tlb.c
> > +++ b/lib/sbi/sbi_tlb.c
> > @@ -72,7 +72,7 @@ void sbi_tlb_local_hfence_gvma(struct sbi_tlb_info
> > *tinfo)
> >         }
> >
> >         for (i = 0; i < size; i += PAGE_SIZE) {
> > -               __sbi_hfence_gvma_gpa(start+i);
> > +               __sbi_hfence_gvma_gpa((start + i) >> 2);
> >         }
> >  }
> >
> > @@ -148,7 +148,7 @@ void sbi_tlb_local_hfence_gvma_vmid(struct
> > sbi_tlb_info *tinfo)
> >         }
> >
> >         for (i = 0; i < size; i += PAGE_SIZE) {
> > -               __sbi_hfence_gvma_vmid_gpa(start + i, vmid);
> > +               __sbi_hfence_gvma_vmid_gpa((start + i) >> 2, vmid);
> >         }
> >  }
> >
> > --
> > 2.25.1
> >
> >
>
>