Re: [Qemu-devel] [PATCH 2/7] pci: memory access API and IOMMU support

[Stefan Weil <weil@mail.berlios.de>]

Please see my comments at the end of this mail.


Am 30.08.2010 00:08, schrieb Eduard - Gabriel Munteanu:
> PCI devices should access memory through pci_memory_*() instead of
> cpu_physical_memory_*(). This also provides support for translation and
> access checking in case an IOMMU is emulated.
>
> Memory maps are treated as remote IOTLBs (that is, translation caches
> belonging to the IOMMU-aware device itself). Clients (devices) must
> provide callbacks for map invalidation in case these maps are
> persistent beyond the current I/O context, e.g. AIO DMA transfers.
>
> Signed-off-by: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
> ---
> hw/pci.c | 191 +++++++++++++++++++++++++++++++++++++++++++++++++++-
> hw/pci.h | 69 +++++++++++++++++++
> hw/pci_internals.h | 12 +++
> qemu-common.h | 1 +
> 4 files changed, 272 insertions(+), 1 deletions(-)
>
> diff --git a/hw/pci.c b/hw/pci.c
> index 2dc1577..afcb33c 100644
> --- a/hw/pci.c
> +++ b/hw/pci.c
>
> ...
>
> diff --git a/hw/pci.h b/hw/pci.h
> index c551f96..c95863a 100644
> --- a/hw/pci.h
> +++ b/hw/pci.h
> @@ -172,6 +172,8 @@ struct PCIDevice {
> char *romfile;
> ram_addr_t rom_offset;
> uint32_t rom_bar;
> +
> + QLIST_HEAD(, PCIMemoryMap) memory_maps;
> };
>
> PCIDevice *pci_register_device(PCIBus *bus, const char *name,
> @@ -391,4 +393,71 @@ static inline int ranges_overlap(uint64_t first1, 
> uint64_t len1,
> return !(last2 < first1 || last1 < first2);
> }
>
> +/*
> + * Memory I/O and PCI IOMMU definitions.
> + */
> +
> +#define IOMMU_PERM_READ (1 << 0)
> +#define IOMMU_PERM_WRITE (1 << 1)
> +#define IOMMU_PERM_RW (IOMMU_PERM_READ | IOMMU_PERM_WRITE)
> +
> +typedef int PCIInvalidateMapFunc(void *opaque);
> +typedef int PCITranslateFunc(PCIDevice *iommu,
> + PCIDevice *dev,
> + pcibus_t addr,
> + target_phys_addr_t *paddr,
> + target_phys_addr_t *len,
> + unsigned perms);
> +
> +void pci_memory_rw(PCIDevice *dev,
> + pcibus_t addr,
> + uint8_t *buf,
> + pcibus_t len,
> + int is_write);
> +void *pci_memory_map(PCIDevice *dev,
> + PCIInvalidateMapFunc *cb,
> + void *opaque,
> + pcibus_t addr,
> + target_phys_addr_t *len,
> + int is_write);
> +void pci_memory_unmap(PCIDevice *dev,
> + void *buffer,
> + target_phys_addr_t len,
> + int is_write,
> + target_phys_addr_t access_len);
> +void pci_register_iommu(PCIDevice *dev, PCITranslateFunc *translate);
> +void pci_memory_invalidate_range(PCIDevice *dev, pcibus_t addr, 
> pcibus_t len);
> +
> +#define DECLARE_PCI_LD(suffix, size) \
> +uint##size##_t pci_ld##suffix(PCIDevice *dev, pcibus_t addr);
> +
> +#define DECLARE_PCI_ST(suffix, size) \
> +void pci_st##suffix(PCIDevice *dev, pcibus_t addr, uint##size##_t val);
> +
> +DECLARE_PCI_LD(ub, 8)
> +DECLARE_PCI_LD(uw, 16)
> +DECLARE_PCI_LD(l, 32)
> +DECLARE_PCI_LD(q, 64)
> +
> +DECLARE_PCI_ST(b, 8)
> +DECLARE_PCI_ST(w, 16)
> +DECLARE_PCI_ST(l, 32)
> +DECLARE_PCI_ST(q, 64)
> +
> +static inline void pci_memory_read(PCIDevice *dev,
> + pcibus_t addr,
> + uint8_t *buf,
> + pcibus_t len)
> +{
> + pci_memory_rw(dev, addr, buf, len, 0);
> +}
> +
> +static inline void pci_memory_write(PCIDevice *dev,
> + pcibus_t addr,
> + const uint8_t *buf,
> + pcibus_t len)
> +{
> + pci_memory_rw(dev, addr, (uint8_t *) buf, len, 1);
> +}
> +
> #endif

The functions pci_memory_read and pci_memory_write not only read
or write byte data but many different data types which leads to
a lot of type casts in your other patches.

I'd prefer "void *buf" and "const void *buf" in the argument lists.
Then all those type casts could be removed.

Regards
Stefan Weil