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From: "Michael S. Tsirkin" <mst@redhat.com>
To: Kuppuswamy Sathyanarayanan  <sathyanarayanan.kuppuswamy@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Peter Zijlstra <peterz@infradead.org>,
	Andy Lutomirski <luto@kernel.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Richard Henderson <rth@twiddle.net>,
	Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	James E J Bottomley <James.Bottomley@hansenpartnership.com>,
	Helge Deller <deller@gmx.de>,
	"David S . Miller" <davem@davemloft.net>,
	Arnd Bergmann <arnd@arndb.de>, Jonathan Corbet <corbet@lwn.net>,
	Peter H Anvin <hpa@zytor.com>,
	Dave Hansen <dave.hansen@intel.com>,
	Tony Luck <tony.luck@intel.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Andi Kleen <ak@linux.intel.com>,
	Kirill Shutemov <kirill.shutemov@linux.intel.com>,
	Sean Christopherson <seanjc@google.com>,
	Kuppuswamy Sathyanarayanan <knsathya@kernel.org>,
	x86@kernel.org, linux-kernel@vger.kernel.org,
	linux-pci@vger.kernel.org, linux-alpha@vger.kernel.org,
	linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org,
	sparclinux@vger.kernel.org, linux-arch@vger.kernel.org,
	linux-doc@vger.kernel.org,
	virtualization@lists.linux-foundation.org
Subject: Re: [PATCH v4 11/15] pci: Add pci_iomap_shared{,_range}
Date: Mon, 23 Aug 2021 19:56:03 -0400	[thread overview]
Message-ID: <20210823195409-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20210805005218.2912076-12-sathyanarayanan.kuppuswamy@linux.intel.com>

On Wed, Aug 04, 2021 at 05:52:14PM -0700, Kuppuswamy Sathyanarayanan wrote:
> From: Andi Kleen <ak@linux.intel.com>
> 
> 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 <ak@linux.intel.com>
> 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!

> ---
>  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


  parent reply	other threads:[~2021-08-23 23:56 UTC|newest]

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-05  0:52 [PATCH v4 00/15] Add TDX Guest Support (shared-mm support) Kuppuswamy Sathyanarayanan
2021-08-05  0:52 ` [PATCH v4 01/15] x86/mm: Move force_dma_unencrypted() to common code Kuppuswamy Sathyanarayanan
2021-08-05  0:52 ` [PATCH v4 02/15] x86/tdx: Exclude Shared bit from physical_mask Kuppuswamy Sathyanarayanan
2021-08-05  0:52 ` [PATCH v4 03/15] x86/tdx: Make pages shared in ioremap() Kuppuswamy Sathyanarayanan
2021-08-05  0:52 ` [PATCH v4 04/15] x86/tdx: Add helper to do MapGPA hypercall Kuppuswamy Sathyanarayanan
2021-08-05  0:52 ` [PATCH v4 05/15] x86/tdx: Make DMA pages shared Kuppuswamy Sathyanarayanan
2021-08-05  0:52 ` [PATCH v4 06/15] x86/kvm: Use bounce buffers for TD guest Kuppuswamy Sathyanarayanan
2021-08-05  0:52 ` [PATCH v4 07/15] x86/tdx: ioapic: Add shared bit for IOAPIC base address Kuppuswamy Sathyanarayanan
2021-08-05  0:52 ` [PATCH v4 08/15] x86/tdx: Enable shared memory protected guest flags for TDX guest Kuppuswamy Sathyanarayanan
2021-08-05  0:52 ` [PATCH v4 09/15] pci: Consolidate pci_iomap* and pci_iomap*wc Kuppuswamy Sathyanarayanan
2021-08-12 19:43   ` Bjorn Helgaas
2021-08-12 22:11     ` Andi Kleen
2021-08-12 22:29     ` Kuppuswamy, Sathyanarayanan
2021-08-05  0:52 ` [PATCH v4 10/15] asm/io.h: Add ioremap_shared fallback Kuppuswamy Sathyanarayanan
2021-08-12 19:46   ` Bjorn Helgaas
2021-08-13  7:58   ` Christoph Hellwig
2021-08-05  0:52 ` [PATCH v4 11/15] pci: Add pci_iomap_shared{,_range} Kuppuswamy Sathyanarayanan
2021-08-13  8:02   ` Christoph Hellwig
2021-08-23 23:56   ` Michael S. Tsirkin [this message]
2021-08-24  0:30     ` Kuppuswamy, Sathyanarayanan
2021-08-24  1:04       ` Dan Williams
2021-08-24  2:14         ` Andi Kleen
2021-08-24  9:47           ` Michael S. Tsirkin
2021-08-24 17:20             ` Andi Kleen
2021-08-24 18:55               ` Bjorn Helgaas
2021-08-24 20:14                 ` Andi Kleen
2021-08-24 20:31                   ` Bjorn Helgaas
2021-08-24 20:50                     ` Andi Kleen
2021-08-24 21:05                       ` Dan Williams
2021-08-25 14:52                       ` Bjorn Helgaas
2021-08-24 21:55                 ` Rajat Jain
2021-08-29 15:27               ` Michael S. Tsirkin
2021-08-29 16:17                 ` Andi Kleen
2021-08-29 22:26                   ` Michael S. Tsirkin
2021-08-30  5:11                     ` Andi Kleen
2021-08-30 20:59                       ` Michael S. Tsirkin
2021-08-31  0:23                         ` Andi Kleen
2021-09-10  9:54                           ` Michael S. Tsirkin
2021-09-10 16:34                             ` Andi Kleen
2021-09-11 23:54                               ` Michael S. Tsirkin
2021-09-13  5:53                                 ` Michael S. Tsirkin
2021-09-24 22:43                                 ` Andi Kleen
2021-09-27  9:07                                   ` Michael S. Tsirkin
2021-08-24 21:56         ` Rajat Jain
2021-08-24 21:59           ` Dan Williams
2021-08-24  7:07       ` Christoph Hellwig
2021-08-24 17:04         ` Andi Kleen
2021-08-29 15:34           ` Michael S. Tsirkin
2021-08-29 16:43             ` Andi Kleen
2021-08-24  9:12       ` Michael S. Tsirkin
2021-08-05  0:52 ` [PATCH v4 12/15] pci: Mark MSI data shared Kuppuswamy Sathyanarayanan
2021-08-13  8:07   ` Christoph Hellwig
2021-08-05  0:52 ` [PATCH v4 13/15] virtio: Use shared mappings for virtio PCI devices Kuppuswamy Sathyanarayanan
2021-08-05  0:52 ` [PATCH v4 14/15] x86/tdx: Implement ioremap_shared for x86 Kuppuswamy Sathyanarayanan
2021-08-05  0:52 ` [PATCH v4 15/15] x86/tdx: Add cmdline option to force use of ioremap_shared Kuppuswamy Sathyanarayanan

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