| Message ID | 1448372127-28115-3-git-send-email-tianyu.lan@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, 2015-11-24 at 21:35 +0800, Lan Tianyu wrote: > Signed-off-by: Lan Tianyu <tianyu.lan@intel.com> > --- > linux-headers/linux/vfio.h | 16 ++++++++++++++++ > 1 file changed, 16 insertions(+) > > diff --git a/linux-headers/linux/vfio.h b/linux-headers/linux/vfio.h > index 0508d0b..732b0bd 100644 > --- a/linux-headers/linux/vfio.h > +++ b/linux-headers/linux/vfio.h > @@ -495,6 +495,22 @@ struct vfio_eeh_pe_op { > > #define VFIO_EEH_PE_OP _IO(VFIO_TYPE, VFIO_BASE + 21) > > + > +#define VFIO_FIND_FREE_PCI_CONFIG_REG _IO(VFIO_TYPE, VFIO_BASE + 22) > + > +#define VFIO_GET_PCI_CAP_INFO _IO(VFIO_TYPE, VFIO_BASE + 22) > + > +struct vfio_pci_cap_info { > + __u32 argsz; > + __u32 flags; > +#define VFIO_PCI_CAP_GET_SIZE (1 << 0) > +#define VFIO_PCI_CAP_GET_FREE_REGION (1 << 1) > + __u32 index; > + __u32 offset; > + __u32 size; > + __u8 cap; > +}; > + > /* ***************************************************************** */ > > #endif /* VFIO_H */ I didn't seen a matching kernel patch series for this, but why is the kernel more capable of doing this than userspace is already? These seem like pointless ioctls, we're creating a purely virtual PCI capability, the kernel doesn't really need to participate in that. Also, why are we restricting ourselves to standard capabilities? That's often a crowded space and we can't always know whether an area is free or not based only on it being covered by a capability. Some capabilities can also appear more than once, so there's context that isn't being passed to the kernel here. Thanks, Alex -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 12/3/2015 6:25 AM, Alex Williamson wrote: > I didn't seen a matching kernel patch series for this, but why is the > kernel more capable of doing this than userspace is already? The following link is the kernel patch. http://marc.info/?l=kvm&m=144837328920989&w=2 > These seem > like pointless ioctls, we're creating a purely virtual PCI capability, > the kernel doesn't really need to participate in that. VFIO kernel driver has pci_config_map which indicates the PCI capability position and length which helps to find free PCI config regs. Qemu side doesn't have such info and can't get the exact table size of PCI capability. If we want to add such support in the Qemu, needs duplicates a lot of code of vfio_pci_configs.c in the Qemu. > Also, why are we > restricting ourselves to standard capabilities? This version is to check whether it's on the right way and We can extend this to pci extended capability later. > That's often a crowded > space and we can't always know whether an area is free or not based only > on it being covered by a capability. Some capabilities can also appear > more than once, so there's context that isn't being passed to the kernel > here. Thanks, The region outside of PCI capability are not passed to kernel or used by Qemu for MSI/MSIX . It's possible to use these places for new capability. One concerns is that guest driver may abuse them and quirk of masking some special regs outside of capability maybe helpful. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, 2015-12-03 at 16:40 +0800, Lan, Tianyu wrote: > On 12/3/2015 6:25 AM, Alex Williamson wrote: > > I didn't seen a matching kernel patch series for this, but why is the > > kernel more capable of doing this than userspace is already? > The following link is the kernel patch. > http://marc.info/?l=kvm&m=144837328920989&w=2 > > > These seem > > like pointless ioctls, we're creating a purely virtual PCI capability, > > the kernel doesn't really need to participate in that. > > VFIO kernel driver has pci_config_map which indicates the PCI capability > position and length which helps to find free PCI config regs. Qemu side > doesn't have such info and can't get the exact table size of PCI > capability. If we want to add such support in the Qemu, needs duplicates > a lot of code of vfio_pci_configs.c in the Qemu. That's an internal implementation detail of the kernel, not motivation for creating a new userspace ABI. QEMU can recreate this data on its own. The kernel is in no more of an authoritative position to determine capability extents than userspace. > > Also, why are we > > restricting ourselves to standard capabilities? > > This version is to check whether it's on the right way and We can extend > this to pci extended capability later. > > > That's often a crowded > > space and we can't always know whether an area is free or not based only > > on it being covered by a capability. Some capabilities can also appear > > more than once, so there's context that isn't being passed to the kernel > > here. Thanks, > > The region outside of PCI capability are not passed to kernel or used by > Qemu for MSI/MSIX . It's possible to use these places for new > capability. One concerns is that guest driver may abuse them and quirk > of masking some special regs outside of capability maybe helpful. That's not correct, see kernel commit a7d1ea1c11b33bda2691f3294b4d735ed635535a. Gaps between capabilities are exposed with raw read-write access from the kernel and some drivers and devices depend on this. There's also no guarantee that there's a sufficiently sized gap in conventional space. Thanks, Alex -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/linux-headers/linux/vfio.h b/linux-headers/linux/vfio.h index 0508d0b..732b0bd 100644 --- a/linux-headers/linux/vfio.h +++ b/linux-headers/linux/vfio.h @@ -495,6 +495,22 @@ struct vfio_eeh_pe_op { #define VFIO_EEH_PE_OP _IO(VFIO_TYPE, VFIO_BASE + 21) + +#define VFIO_FIND_FREE_PCI_CONFIG_REG _IO(VFIO_TYPE, VFIO_BASE + 22) + +#define VFIO_GET_PCI_CAP_INFO _IO(VFIO_TYPE, VFIO_BASE + 22) + +struct vfio_pci_cap_info { + __u32 argsz; + __u32 flags; +#define VFIO_PCI_CAP_GET_SIZE (1 << 0) +#define VFIO_PCI_CAP_GET_FREE_REGION (1 << 1) + __u32 index; + __u32 offset; + __u32 size; + __u8 cap; +}; + /* ***************************************************************** */ #endif /* VFIO_H */
Signed-off-by: Lan Tianyu <tianyu.lan@intel.com> --- linux-headers/linux/vfio.h | 16 ++++++++++++++++ 1 file changed, 16 insertions(+)