Re: [PATCH] s390: PCI: fix IOMMU region init

2019-09-27 Thread Christian Borntraeger
On 26.09.19 16:10, Matthew Rosato wrote: > The fix in dbe9cf606c shrinks the IOMMU memory region to a size > that seems reasonable on the surface, however is actually too > small as it is based against a 0-mapped address space. This > causes breakage with small guests as they can overrun the IO

Re: [PATCH] s390: PCI: fix IOMMU region init

2019-09-27 Thread Christian Borntraeger
On 26.09.19 16:10, Matthew Rosato wrote: > The fix in dbe9cf606c shrinks the IOMMU memory region to a size > that seems reasonable on the surface, however is actually too > small as it is based against a 0-mapped address space. This > causes breakage with small guests as they can overrun the IOMMU

Re: [PATCH] s390: PCI: fix IOMMU region init

2019-09-27 Thread Christian Borntraeger
On 26.09.19 16:34, Peter Maydell wrote: > On Thu, 26 Sep 2019 at 15:12, Matthew Rosato wrote: >> >> The fix in dbe9cf606c shrinks the IOMMU memory region to a size >> that seems reasonable on the surface, however is actually too >> small as it is based against a 0-mapped address space. This >>

Re: [PATCH] s390: PCI: fix IOMMU region init

2019-09-26 Thread Matthew Rosato
On 9/26/19 10:34 AM, Peter Maydell wrote: > On Thu, 26 Sep 2019 at 15:12, Matthew Rosato wrote: >> >> The fix in dbe9cf606c shrinks the IOMMU memory region to a size >> that seems reasonable on the surface, however is actually too >> small as it is based against a 0-mapped address space. This >>

Re: [PATCH] s390: PCI: fix IOMMU region init

2019-09-26 Thread Peter Maydell
On Thu, 26 Sep 2019 at 15:12, Matthew Rosato wrote: > > The fix in dbe9cf606c shrinks the IOMMU memory region to a size > that seems reasonable on the surface, however is actually too > small as it is based against a 0-mapped address space. This > causes breakage with small guests as they can ove

Re: [PATCH] s390: PCI: fix IOMMU region init

2019-09-26 Thread Pierre Morel
Yes, it is the right thing to do. We will see if we one of these day can fix the address space size and get rid of the access to the lower memory. The iommu region translation callback protect us from setting a translation outside of pba-pal, so that we should be safe. reviewed-by: Pierre

[PATCH] s390: PCI: fix IOMMU region init

2019-09-26 Thread Matthew Rosato
The fix in dbe9cf606c shrinks the IOMMU memory region to a size that seems reasonable on the surface, however is actually too small as it is based against a 0-mapped address space. This causes breakage with small guests as they can overrun the IOMMU window. Let's go back to the prior method of in