[PATCH] vfio/pci: Fallback huge faults for unaligned pfn

[PATCH] vfio/pci: Fallback huge faults for unaligned pfn

[Alex Williamson]

The PFN must also be aligned to the fault order to insert a huge
pfnmap.  Test the alignment and fallback when unaligned.

Fixes: f9e54c3a2f5b ("vfio/pci: implement huge_fault support")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=219619
Reported-by: Athul Krishna <athul.krishna.kr@protonmail.com>
Reported-by: Precific <precification@posteo.de>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---
 drivers/vfio/pci/vfio_pci_core.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index 1ab58da9f38a..1a4ed5a357d3 100644
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -1661,14 +1661,15 @@ static vm_fault_t vfio_pci_mmap_huge_fault(struct vm_fault *vmf,
 	unsigned long pfn, pgoff = vmf->pgoff - vma->vm_pgoff;
 	vm_fault_t ret = VM_FAULT_SIGBUS;
 
-	if (order && (vmf->address & ((PAGE_SIZE << order) - 1) ||
+	pfn = vma_to_pfn(vma) + pgoff;
+
+	if (order && (pfn & ((1 << order) - 1) ||
+		      vmf->address & ((PAGE_SIZE << order) - 1) ||
 		      vmf->address + (PAGE_SIZE << order) > vma->vm_end)) {
 		ret = VM_FAULT_FALLBACK;
 		goto out;
 	}
 
-	pfn = vma_to_pfn(vma);
-
 	down_read(&vdev->memory_lock);
 
 	if (vdev->pm_runtime_engaged || !__vfio_pci_memory_enabled(vdev))
@@ -1676,18 +1677,18 @@ static vm_fault_t vfio_pci_mmap_huge_fault(struct vm_fault *vmf,
 
 	switch (order) {
 	case 0:
-		ret = vmf_insert_pfn(vma, vmf->address, pfn + pgoff);
+		ret = vmf_insert_pfn(vma, vmf->address, pfn);
 		break;
 #ifdef CONFIG_ARCH_SUPPORTS_PMD_PFNMAP
 	case PMD_ORDER:
-		ret = vmf_insert_pfn_pmd(vmf, __pfn_to_pfn_t(pfn + pgoff,
-							     PFN_DEV), false);
+		ret = vmf_insert_pfn_pmd(vmf,
+					 __pfn_to_pfn_t(pfn, PFN_DEV), false);
 		break;
 #endif
 #ifdef CONFIG_ARCH_SUPPORTS_PUD_PFNMAP
 	case PUD_ORDER:
-		ret = vmf_insert_pfn_pud(vmf, __pfn_to_pfn_t(pfn + pgoff,
-							     PFN_DEV), false);
+		ret = vmf_insert_pfn_pud(vmf,
+					 __pfn_to_pfn_t(pfn, PFN_DEV), false);
 		break;
 #endif
 	default:
-- 
2.47.1

Re: [PATCH] vfio/pci: Fallback huge faults for unaligned pfn

[Peter Xu]

On Thu, Jan 02, 2025 at 11:32:54AM -0700, Alex Williamson wrote:
> The PFN must also be aligned to the fault order to insert a huge
> pfnmap.  Test the alignment and fallback when unaligned.
> 
> Fixes: f9e54c3a2f5b ("vfio/pci: implement huge_fault support")
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=219619
> Reported-by: Athul Krishna <athul.krishna.kr@protonmail.com>
> Reported-by: Precific <precification@posteo.de>
> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

Reviewed-by: Peter Xu <peterx@redhat.com>

-- 
Peter Xu

Re: [PATCH] vfio/pci: Fallback huge faults for unaligned pfn

[Greg KH]

On Thu, Jan 02, 2025 at 11:32:54AM -0700, Alex Williamson wrote:
> The PFN must also be aligned to the fault order to insert a huge
> pfnmap.  Test the alignment and fallback when unaligned.
> 
> Fixes: f9e54c3a2f5b ("vfio/pci: implement huge_fault support")
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=219619
> Reported-by: Athul Krishna <athul.krishna.kr@protonmail.com>
> Reported-by: Precific <precification@posteo.de>
> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
> ---
>  drivers/vfio/pci/vfio_pci_core.c | 17 +++++++++--------
>  1 file changed, 9 insertions(+), 8 deletions(-)
> 

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
a patch that has triggered this response.  He used to manually respond
to these common problems, but in order to save his sanity (he kept
writing the same thing over and over, yet to different people), I was
created.  Hopefully you will not take offence and will fix the problem
in your patch and resubmit it so that it can be accepted into the Linux
kernel tree.

You are receiving this message because of the following common error(s)
as indicated below:

- You have marked a patch with a "Fixes:" tag for a commit that is in an
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  this.

If you wish to discuss this problem further, or you have questions about
how to resolve this issue, please feel free to respond to this email and
Greg will reply once he has dug out from the pending patches received
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thanks,

greg k-h's patch email bot

Re: [PATCH] vfio/pci: Fallback huge faults for unaligned pfn

[Precific]

On Thu, Jan 02, 2025 at 19:32:54 +0100, Alex Williamson wrote:
> The PFN must also be aligned to the fault order to insert a huge
> pfnmap.  Test the alignment and fallback when unaligned.
> 
> Fixes: f9e54c3a2f5b ("vfio/pci: implement huge_fault support")
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=219619
> Reported-by: Athul Krishna <athul.krishna.kr@protonmail.com>
> Reported-by: Precific <precification@posteo.de>
> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

Tested-by: Precific <precification@posteo.de>