Re: [PATCH RESEND 1/2] riscv: mm: Apply svinval in update_mmu_cache()

[Anirudh Srinivasan]

On Wed, Jul 15, 2026 at 03:14:25AM +0200, Klara Modin wrote:
> Hi,
> 
> On 2025-09-01 19:41:40 +0800, Xu Lu wrote:
> > Only flush tlb of the specified mm, and apply svinval if available.
> > 
> > Signed-off-by: Xu Lu <luxu.kernel@xxxxxxxxxxxxx>
> > ---
> >  arch/riscv/include/asm/pgtable.h  | 16 +++++++++++++++-
> >  arch/riscv/include/asm/tlbflush.h | 23 +++++++++++++++++++++++
> >  arch/riscv/mm/tlbflush.c          | 23 -----------------------
> >  3 files changed, 38 insertions(+), 24 deletions(-)
> > 
> > diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
> > index 91697fbf1f901..165cd02d51629 100644
> > --- a/arch/riscv/include/asm/pgtable.h
> > +++ b/arch/riscv/include/asm/pgtable.h
> > @@ -495,9 +495,15 @@ static inline void update_mmu_cache_range(struct vm_fault *vmf,
> >  		struct vm_area_struct *vma, unsigned long address,
> >  		pte_t *ptep, unsigned int nr)
> >  {
> > +	int i;
> > +	unsigned long asid = get_mm_asid(vma->vm_mm);
> > +
> >  	asm goto(ALTERNATIVE("nop", "j %l[svvptc]", 0, RISCV_ISA_EXT_SVVPTC, 1)
> >  		 : : : : svvptc);
> >  
> > +	asm goto(ALTERNATIVE("nop", "j %l[svinval]", 0, RISCV_ISA_EXT_SVINVAL, 1)
> > +		 : : : : svinval);
> > +
> >  	/*
> >  	 * The kernel assumes that TLBs don't cache invalid entries, but
> >  	 * in RISC-V, SFENCE.VMA specifies an ordering constraint, not a
> > @@ -506,7 +512,15 @@ static inline void update_mmu_cache_range(struct vm_fault *vmf,
> >  	 * the extra traps reduce performance.  So, eagerly SFENCE.VMA.
> >  	 */
> >  	while (nr--)
> > -		local_flush_tlb_page(address + nr * PAGE_SIZE);
> > +		local_flush_tlb_page_asid(address + nr * PAGE_SIZE, asid);
> > +	return;
> > +
> > +svinval:
> > +	local_sfence_w_inval();
> 
> > +	for (i = 0; i < nr; i++)
> > +		local_sinval_vma(address + nr * PAGE_SIZE, asid);
> 
> Probably should be
> 
>  +	for (i = 0; i < nr; i++)
>  +		local_sinval_vma(address + i * PAGE_SIZE, asid);
> 
> instead. My BPI-f3 hangs when entering the initramfs with the original
> patch. Reverting also fixes it.

I'm also noticing this. linux-next is unable to enter userspace due to
this on Spacemit K1. Hopefully we can get a fix merged in soon.

Regards
Anirudh Srinivasan

> 
> > +	local_sfence_inval_ir();
> > +	return;
> >  
> >  svvptc:;
> >  	/*
> 
> Regards,
> Klara Modin
> 
> ...