Re: [PATCH v7] swiotlb: Adjust SWIOTBL bounce buffer size for SEV guests.

2020-12-07 Thread Borislav Petkov
On Mon, Dec 07, 2020 at 10:20:20PM +, Kalra, Ashish wrote: > It is more of an approximation of the earlier static adjustment which > was 128M for <1G guests, 256M for 1G-4G guests and 512M for >4G > guests. Makes sense and it is better than nothing. Please put that explanation over the 6%

Re: [PATCH v7] swiotlb: Adjust SWIOTBL bounce buffer size for SEV guests.

2020-12-07 Thread Kalra, Ashish
> On Dec 7, 2020, at 4:14 PM, Borislav Petkov wrote: > > On Mon, Dec 07, 2020 at 10:06:24PM +, Ashish Kalra wrote: >> This is related to the earlier static adjustment of the SWIOTLB buffers >> as per guest memory size and Konrad's feedback on the same, as copied >> below : >> That

Re: [PATCH v7] swiotlb: Adjust SWIOTBL bounce buffer size for SEV guests.

2020-12-07 Thread Borislav Petkov
On Mon, Dec 07, 2020 at 10:06:24PM +, Ashish Kalra wrote: > This is related to the earlier static adjustment of the SWIOTLB buffers > as per guest memory size and Konrad's feedback on the same, as copied > below : > > >>That is eating 128MB for 1GB, aka 12% of the guest memory allocated >

Re: [PATCH v7] swiotlb: Adjust SWIOTBL bounce buffer size for SEV guests.

2020-12-07 Thread Ashish Kalra
Hello Boris, On Mon, Dec 07, 2020 at 01:10:07PM +0100, Borislav Petkov wrote: > On Thu, Dec 03, 2020 at 03:25:59AM +, Ashish Kalra wrote: > > diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c > > index 1bcfbcd2bfd7..46549bd3d840 100644 > > --- a/arch/x86/mm/mem_encrypt.c > >

Re: [PATCH v7] swiotlb: Adjust SWIOTBL bounce buffer size for SEV guests.

2020-12-07 Thread Borislav Petkov
On Thu, Dec 03, 2020 at 03:25:59AM +, Ashish Kalra wrote: > diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c > index 1bcfbcd2bfd7..46549bd3d840 100644 > --- a/arch/x86/mm/mem_encrypt.c > +++ b/arch/x86/mm/mem_encrypt.c > @@ -485,7 +485,38 @@ static void

[PATCH v7] swiotlb: Adjust SWIOTBL bounce buffer size for SEV guests.

2020-12-02 Thread Ashish Kalra
From: Ashish Kalra For SEV, all DMA to and from guest has to use shared (un-encrypted) pages. SEV uses SWIOTLB to make this happen without requiring changes to device drivers. However, depending on workload being run, the default 64MB of SWIOTLB might not be enough and SWIOTLB may run out of