| Message ID | 20231012220854.2736994-2-volodymyr_babchuk@epam.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | PCI devices passthrough on Arm, part 3 | expand |
On 13.10.2023 00:09, Volodymyr Babchuk wrote: > Previously pci_enable_msi() function obtained pdev pointer by itself, > but taking into account upcoming changes to PCI locking, it is better > when caller passes already acquired pdev pointer to the function. For the patch to be understandable on its own, the "is better" wants explaining here. > Note that ns16550 driver does not check validity of obtained pdev > pointer because pci_enable_msi() already does this. I'm not convinced of this model. I'd rather see the caller do the check, and the callee - optionally - have a respective assertion. > --- a/xen/arch/x86/msi.c > +++ b/xen/arch/x86/msi.c > @@ -983,13 +983,13 @@ static int msix_capability_init(struct pci_dev *dev, > * irq or non-zero for otherwise. > **/ > > -static int __pci_enable_msi(struct msi_info *msi, struct msi_desc **desc) > +static int __pci_enable_msi(struct msi_info *msi, struct msi_desc **desc, > + struct pci_dev *pdev) In line with msi_capability_init() and ... > @@ -1038,13 +1038,13 @@ static void __pci_disable_msi(struct msi_desc *entry) > * of irqs available. Driver should use the returned value to re-send > * its request. > **/ > -static int __pci_enable_msix(struct msi_info *msi, struct msi_desc **desc) > +static int __pci_enable_msix(struct msi_info *msi, struct msi_desc **desc, > + struct pci_dev *pdev) ... msix_capability_init(), may I ask that the new parameter then become the first one, not the last (and hence even past output parameters)? Jan
On Thu, Oct 12, 2023 at 10:09:14PM +0000, Volodymyr Babchuk wrote: > Previously pci_enable_msi() function obtained pdev pointer by itself, > but taking into account upcoming changes to PCI locking, it is better > when caller passes already acquired pdev pointer to the function. A bit more detail into why this matters for the upcoming locking change would be useful here. > Note that ns16550 driver does not check validity of obtained pdev > pointer because pci_enable_msi() already does this. > > Signed-off-by: Volodymyr Babchuk <volodymyr_babchuk@epam.com> > > --- > Changes in v10: > > - New in v10. This is the result of discussion in "vpci: add initial > support for virtual PCI bus topology" > --- > xen/arch/x86/include/asm/msi.h | 3 ++- > xen/arch/x86/irq.c | 2 +- > xen/arch/x86/msi.c | 19 ++++++++++--------- > xen/drivers/char/ns16550.c | 4 +++- > 4 files changed, 16 insertions(+), 12 deletions(-) > > diff --git a/xen/arch/x86/include/asm/msi.h b/xen/arch/x86/include/asm/msi.h > index a53ade95c9..836c8cd4ba 100644 > --- a/xen/arch/x86/include/asm/msi.h > +++ b/xen/arch/x86/include/asm/msi.h > @@ -81,7 +81,8 @@ struct irq_desc; > struct hw_interrupt_type; > struct msi_desc; > /* Helper functions */ > -extern int pci_enable_msi(struct msi_info *msi, struct msi_desc **desc); > +extern int pci_enable_msi(struct msi_info *msi, struct msi_desc **desc, > + struct pci_dev *pdev); Hard tabs (here and below). I agree with Jan that it might be better for pdev to be the first parameter. Otherwise seems fine if the pdev is already in the caller context, as we avoid an extra list walk. Thanks, Roger.
diff --git a/xen/arch/x86/include/asm/msi.h b/xen/arch/x86/include/asm/msi.h index a53ade95c9..836c8cd4ba 100644 --- a/xen/arch/x86/include/asm/msi.h +++ b/xen/arch/x86/include/asm/msi.h @@ -81,7 +81,8 @@ struct irq_desc; struct hw_interrupt_type; struct msi_desc; /* Helper functions */ -extern int pci_enable_msi(struct msi_info *msi, struct msi_desc **desc); +extern int pci_enable_msi(struct msi_info *msi, struct msi_desc **desc, + struct pci_dev *pdev); extern void pci_disable_msi(struct msi_desc *desc); extern int pci_prepare_msix(u16 seg, u8 bus, u8 devfn, bool off); extern void pci_cleanup_msi(struct pci_dev *pdev); diff --git a/xen/arch/x86/irq.c b/xen/arch/x86/irq.c index 6abfd81621..68b788c42e 100644 --- a/xen/arch/x86/irq.c +++ b/xen/arch/x86/irq.c @@ -2167,7 +2167,7 @@ int map_domain_pirq( if ( !pdev ) goto done; - ret = pci_enable_msi(msi, &msi_desc); + ret = pci_enable_msi(msi, &msi_desc, pdev); if ( ret ) { if ( ret > 0 ) diff --git a/xen/arch/x86/msi.c b/xen/arch/x86/msi.c index a78367d7cf..20275260b3 100644 --- a/xen/arch/x86/msi.c +++ b/xen/arch/x86/msi.c @@ -983,13 +983,13 @@ static int msix_capability_init(struct pci_dev *dev, * irq or non-zero for otherwise. **/ -static int __pci_enable_msi(struct msi_info *msi, struct msi_desc **desc) +static int __pci_enable_msi(struct msi_info *msi, struct msi_desc **desc, + struct pci_dev *pdev) { - struct pci_dev *pdev; struct msi_desc *old_desc; ASSERT(pcidevs_locked()); - pdev = pci_get_pdev(NULL, msi->sbdf); + if ( !pdev ) return -ENODEV; @@ -1038,13 +1038,13 @@ static void __pci_disable_msi(struct msi_desc *entry) * of irqs available. Driver should use the returned value to re-send * its request. **/ -static int __pci_enable_msix(struct msi_info *msi, struct msi_desc **desc) +static int __pci_enable_msix(struct msi_info *msi, struct msi_desc **desc, + struct pci_dev *pdev) { - struct pci_dev *pdev; struct msi_desc *old_desc; ASSERT(pcidevs_locked()); - pdev = pci_get_pdev(NULL, msi->sbdf); + if ( !pdev || !pdev->msix ) return -ENODEV; @@ -1151,15 +1151,16 @@ int pci_prepare_msix(u16 seg, u8 bus, u8 devfn, bool off) * Notice: only construct the msi_desc * no change to irq_desc here, and the interrupt is masked */ -int pci_enable_msi(struct msi_info *msi, struct msi_desc **desc) +int pci_enable_msi(struct msi_info *msi, struct msi_desc **desc, + struct pci_dev *pdev) { ASSERT(pcidevs_locked()); if ( !use_msi ) return -EPERM; - return msi->table_base ? __pci_enable_msix(msi, desc) : - __pci_enable_msi(msi, desc); + return msi->table_base ? __pci_enable_msix(msi, desc, pdev) : + __pci_enable_msi(msi, desc, pdev); } /* diff --git a/xen/drivers/char/ns16550.c b/xen/drivers/char/ns16550.c index 28ddedd50d..1856b72e63 100644 --- a/xen/drivers/char/ns16550.c +++ b/xen/drivers/char/ns16550.c @@ -452,10 +452,12 @@ static void __init cf_check ns16550_init_postirq(struct serial_port *port) if ( rc > 0 ) { struct msi_desc *msi_desc = NULL; + struct pci_dev *pdev; pcidevs_lock(); - rc = pci_enable_msi(&msi, &msi_desc); + pdev = pci_get_pdev(NULL, msi.sbdf); + rc = pci_enable_msi(&msi, &msi_desc, pdev); if ( !rc ) { struct irq_desc *desc = irq_to_desc(msi.irq);
Previously pci_enable_msi() function obtained pdev pointer by itself, but taking into account upcoming changes to PCI locking, it is better when caller passes already acquired pdev pointer to the function. Note that ns16550 driver does not check validity of obtained pdev pointer because pci_enable_msi() already does this. Signed-off-by: Volodymyr Babchuk <volodymyr_babchuk@epam.com> --- Changes in v10: - New in v10. This is the result of discussion in "vpci: add initial support for virtual PCI bus topology" --- xen/arch/x86/include/asm/msi.h | 3 ++- xen/arch/x86/irq.c | 2 +- xen/arch/x86/msi.c | 19 ++++++++++--------- xen/drivers/char/ns16550.c | 4 +++- 4 files changed, 16 insertions(+), 12 deletions(-)