Re: [PATCH v4 11/15] pci: Add pci_iomap_shared{,_range}
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2021-08-23 23:56:17
Also in:
linux-alpha, linux-arch, linux-doc, linux-pci, lkml, sparclinux, virtualization
On Wed, Aug 04, 2021 at 05:52:14PM -0700, Kuppuswamy Sathyanarayanan wrote:
From: Andi Kleen <redacted> Add a new variant of pci_iomap for mapping all PCI resources of a devices as shared memory with a hypervisor in a confidential guest. Signed-off-by: Andi Kleen <redacted> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
I'm a bit puzzled by this part. So why should the guest *not* map pci memory as shared? And if the answer is never (as it seems to be) then why not just make regular pci_iomap DTRT? Thanks!
quoted hunk ↗ jump to hunk
--- include/asm-generic/pci_iomap.h | 6 +++++ lib/pci_iomap.c | 46 +++++++++++++++++++++++++++++++++ 2 files changed, 52 insertions(+)diff --git a/include/asm-generic/pci_iomap.h b/include/asm-generic/pci_iomap.h index d4f16dcc2ed7..0178ddd7ad88 100644 --- a/include/asm-generic/pci_iomap.h +++ b/include/asm-generic/pci_iomap.h@@ -18,6 +18,12 @@ extern void __iomem *pci_iomap_range(struct pci_dev *dev, int bar, extern void __iomem *pci_iomap_wc_range(struct pci_dev *dev, int bar, unsigned long offset, unsigned long maxlen); +extern void __iomem *pci_iomap_shared(struct pci_dev *dev, int bar, + unsigned long max); +extern void __iomem *pci_iomap_shared_range(struct pci_dev *dev, int bar, + unsigned long offset, + unsigned long maxlen); + /* Create a virtual mapping cookie for a port on a given PCI device. * Do not call this directly, it exists to make it easier for architectures * to override */diff --git a/lib/pci_iomap.c b/lib/pci_iomap.c index 6251c3f651c6..b04e8689eab3 100644 --- a/lib/pci_iomap.c +++ b/lib/pci_iomap.c@@ -25,6 +25,11 @@ static void __iomem *map_ioremap_wc(phys_addr_t addr, size_t size) return ioremap_wc(addr, size); } +static void __iomem *map_ioremap_shared(phys_addr_t addr, size_t size) +{ + return ioremap_shared(addr, size); +} + static void __iomem *pci_iomap_range_map(struct pci_dev *dev, int bar, unsigned long offset,@@ -101,6 +106,47 @@ void __iomem *pci_iomap_wc_range(struct pci_dev *dev, } EXPORT_SYMBOL_GPL(pci_iomap_wc_range); +/** + * pci_iomap_shared_range - create a virtual shared mapping cookie for a + * PCI BAR + * @dev: PCI device that owns the BAR + * @bar: BAR number + * @offset: map memory at the given offset in BAR + * @maxlen: max length of the memory to map + * + * Remap a pci device's resources shared in a confidential guest. + * For more details see pci_iomap_range's documentation. + * + * @maxlen specifies the maximum length to map. To get access to + * the complete BAR from offset to the end, pass %0 here. + */ +void __iomem *pci_iomap_shared_range(struct pci_dev *dev, int bar, + unsigned long offset, unsigned long maxlen) +{ + return pci_iomap_range_map(dev, bar, offset, maxlen, + map_ioremap_shared); +} +EXPORT_SYMBOL_GPL(pci_iomap_shared_range); + +/** + * pci_iomap_shared - create a virtual shared mapping cookie for a PCI BAR + * @dev: PCI device that owns the BAR + * @bar: BAR number + * @maxlen: length of the memory to map + * + * See pci_iomap for details. This function creates a shared mapping + * with the host for confidential hosts. + * + * @maxlen specifies the maximum length to map. To get access to the + * complete BAR without checking for its length first, pass %0 here. + */ +void __iomem *pci_iomap_shared(struct pci_dev *dev, int bar, + unsigned long maxlen) +{ + return pci_iomap_shared_range(dev, bar, 0, maxlen); +} +EXPORT_SYMBOL_GPL(pci_iomap_shared); + /** * pci_iomap - create a virtual mapping cookie for a PCI BAR * @dev: PCI device that owns the BAR-- 2.25.1