[PATCH v2] drm/xe: Fix out-of-bounds field write in MI_STORE_DATA_IMM

[Lin, Shuicheng]

Hi maintainers:
Just to avoid this patch be missed, could you please help review and merge it?
Thanks.

Best Regards
Shuicheng

On Wed, May 28, 2025 2:26 AM Brost, Matthew wrote:
> On Tue, May 27, 2025 at 04:30:50PM +0000, Jia Yao wrote:
> > According to Bspec, bits 0~9 of MI_STORE_DATA_IMM must not exceed 0x3FE.
> > The macro MI_SDI_NUM_QW(x) evaluates to 2 * x + 1, which means the
> > condition 2 * x + 1 <= 0x3FE must be satisfied. Therefore, the maximum
> > valid value for x is 0x1FE, not 0x1FF.
> >
> > v2
> >  - Replace 0x1fe with macro MAX_PTE_PER_SDI (Auld, Matthew &
> > Patelczyk, Maciej)
> >
> > Bspec: 60246
> >
> > Fixes: 9c44fd5f6e8a ("drm/xe: Add migrate layer functions for SVM
> > support")
> > Cc: Matthew Brost <matthew.brost at intel.com>
> 
> Thanks for the fix:
> Reviewed-by: Matthew Brost <matthew.brost at intel.com>
> 
> > Cc: Brian3 Nguyen <brian3.nguyen at intel.com>
> > Cc: Alex Zuo <alex.zuo at intel.com>
> > Cc: Matthew Auld <matthew.auld at intel.com>
> > Cc: Maciej Patelczyk <maciej.patelczyk at intel.com>
> > Suggested-by: Shuicheng Lin <shuicheng.lin at intel.com>
> > Signed-off-by: Jia Yao <jia.yao at intel.com>
> > ---
> >  drivers/gpu/drm/xe/xe_migrate.c | 8 ++++----
> >  1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/xe/xe_migrate.c
> > b/drivers/gpu/drm/xe/xe_migrate.c index 8f8e9fdfb2a8..1ede50780a14
> > 100644
> > --- a/drivers/gpu/drm/xe/xe_migrate.c
> > +++ b/drivers/gpu/drm/xe/xe_migrate.c
> > @@ -1555,13 +1555,13 @@ static u32 pte_update_cmd_size(u64 size)
> >  	XE_WARN_ON(size > MAX_PREEMPTDISABLE_TRANSFER);
> >  	/*
> >  	 * MI_STORE_DATA_IMM command is used to update page table. Each
> > -	 * instruction can update maximumly 0x1ff pte entries. To update
> > -	 * n (n <= 0x1ff) pte entries, we need:
> > +	 * instruction can update maximumly 0x1fe pte entries. To update
> > +	 * n (n <= 0x1fe) pte entries, we need:
> >  	 * 1 dword for the MI_STORE_DATA_IMM command header (opcode etc)
> >  	 * 2 dword for the page table's physical location
> >  	 * 2*n dword for value of pte to fill (each pte entry is 2 dwords)
> >  	 */
> > -	num_dword = (1 + 2) * DIV_U64_ROUND_UP(entries, 0x1ff);
> > +	num_dword = (1 + 2) * DIV_U64_ROUND_UP(entries,
> MAX_PTE_PER_SDI);
> >  	num_dword += entries * 2;
> >
> >  	return num_dword;
> > @@ -1577,7 +1577,7 @@ static void build_pt_update_batch_sram(struct
> > xe_migrate *m,
> >
> >  	ptes = DIV_ROUND_UP(size, XE_PAGE_SIZE);
> >  	while (ptes) {
> > -		u32 chunk = min(0x1ffU, ptes);
> > +		u32 chunk = min(MAX_PTE_PER_SDI, ptes);
> >
> >  		bb->cs[bb->len++] = MI_STORE_DATA_IMM |
> MI_SDI_NUM_QW(chunk);
> >  		bb->cs[bb->len++] = pt_offset;
> > --
> > 2.34.1
> >