Re: [PATCH v2 12/30] s390/pci: get SHM information from list pci

Claudio Imbrenda
2022-01-26T10:13:10Z

On Tue, 18 Jan 2022 11:36:06 +0100
Pierre Morel <pmorel@linux.ibm.com> wrote:

> On 1/14/22 21:31, Matthew Rosato wrote:
> > KVM will need information on the special handle mask used to indicate
> > emulated devices. In order to obtain this, a new type of list pci call
> > must be made to gather the information. Extend clp_list_pci_req to
> > also fetch the model-dependent-data field that holds this mask.
> >
> > Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
> > ---
> > arch/s390/include/asm/pci.h | 1 +
> > arch/s390/include/asm/pci_clp.h | 2 +-
> > arch/s390/pci/pci_clp.c | 28 +++++++++++++++++++++++++---
> > 3 files changed, 27 insertions(+), 4 deletions(-)
> >
> > diff --git a/arch/s390/include/asm/pci.h b/arch/s390/include/asm/pci.h
> > index 00a2c24d6d2b..f3cd2da8128c 100644
> > --- a/arch/s390/include/asm/pci.h
> > +++ b/arch/s390/include/asm/pci.h
> > @@ -227,6 +227,7 @@ int clp_enable_fh(struct zpci_dev *zdev, u32 *fh, u8 nr_dma_as);
> > int clp_disable_fh(struct zpci_dev *zdev, u32 *fh);
> > int clp_get_state(u32 fid, enum zpci_state *state);
> > int clp_refresh_fh(u32 fid, u32 *fh);
> > +int zpci_get_mdd(u32 *mdd);
> >
> > /* UID */
> > void update_uid_checking(bool new);
> > diff --git a/arch/s390/include/asm/pci_clp.h b/arch/s390/include/asm/pci_clp.h
> > index 124fadfb74b9..d6bc324763f3 100644
> > --- a/arch/s390/include/asm/pci_clp.h
> > +++ b/arch/s390/include/asm/pci_clp.h
> > @@ -76,7 +76,7 @@ struct clp_req_list_pci {
> > struct clp_rsp_list_pci {
> > struct clp_rsp_hdr hdr;
> > u64 resume_token;
> > - u32 reserved2;
> > + u32 mdd;
> > u16 max_fn;
> > u8 : 7;
> > u8 uid_checking : 1;
> > diff --git a/arch/s390/pci/pci_clp.c b/arch/s390/pci/pci_clp.c
> > index bc7446566cbc..308ffb93413f 100644
> > --- a/arch/s390/pci/pci_clp.c
> > +++ b/arch/s390/pci/pci_clp.c
> > @@ -328,7 +328,7 @@ int clp_disable_fh(struct zpci_dev *zdev, u32 *fh)
> > }
> >
> > static int clp_list_pci_req(struct clp_req_rsp_list_pci *rrb,
> > - u64 *resume_token, int *nentries)
> > + u64 *resume_token, int *nentries, u32 *mdd)
> > {
> > int rc;
> >
> > @@ -354,6 +354,8 @@ static int clp_list_pci_req(struct clp_req_rsp_list_pci *rrb,
> > *nentries = (rrb->response.hdr.len - LIST_PCI_HDR_LEN) /
> > rrb->response.entry_size;
> > *resume_token = rrb->response.resume_token;
> > + if (mdd)
> > + *mdd = rrb->response.mdd;
> >
> > return rc;
> > }
> > @@ -365,7 +367,7 @@ static int clp_list_pci(struct clp_req_rsp_list_pci *rrb, void *data,
> > int nentries, i, rc;
> >
> > do {
> > - rc = clp_list_pci_req(rrb, &resume_token, &nentries);
> > + rc = clp_list_pci_req(rrb, &resume_token, &nentries, NULL);
> > if (rc)
> > return rc;
> > for (i = 0; i < nentries; i++)
> > @@ -383,7 +385,7 @@ static int clp_find_pci(struct clp_req_rsp_list_pci *rrb, u32 fid,
> > int nentries, i, rc;
> >
> > do {
> > - rc = clp_list_pci_req(rrb, &resume_token, &nentries);
> > + rc = clp_list_pci_req(rrb, &resume_token, &nentries, NULL);
> > if (rc)
> > return rc;
> > fh_list = rrb->response.fh_list;
> > @@ -468,6 +470,26 @@ int clp_get_state(u32 fid, enum zpci_state *state)
> > return rc;
> > }
> >
> > +int zpci_get_mdd(u32 *mdd)
> > +{
> > + struct clp_req_rsp_list_pci *rrb;
> > + u64 resume_token = 0;
> > + int nentries, rc;
> > +
> > + if (!mdd)
> > + return -EINVAL;
>
> I think this tests is not useful.
> The caller must take care not to call with a NULL pointer,
> what the only caller today make sure.

what if the caller does it anyway?

I think the test is useful. if passing NULL is a bug, then maybe
consider using BUG_ON, or WARN_ONCE

>
>
> > +
> > + rrb = clp_alloc_block(GFP_KERNEL);
> > + if (!rrb)
> > + return -ENOMEM;
> > +
> > + rc = clp_list_pci_req(rrb, &resume_token, &nentries, mdd);
> > +
> > + clp_free_block(rrb);
> > + return rc;
> > +}
> > +EXPORT_SYMBOL_GPL(zpci_get_mdd);
> > +
> > static int clp_base_slpc(struct clp_req *req, struct clp_req_rsp_slpc *lpcb)
> > {
> > unsigned long limit = PAGE_SIZE - sizeof(lpcb->request);
> >
>