Messages in this thread | | | From | Vishal Annapurve <> | Date | Fri, 2 Feb 2024 10:10:56 +0530 | Subject | Re: [RFC V1 3/5] x86: CVMs: Enable dynamic swiotlb by default for CVMs |
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On Thu, Feb 1, 2024 at 5:50 PM Jeremi Piotrowski <jpiotrowski@linux.microsoft.com> wrote: > > On 12/01/2024 06:52, Vishal Annapurve wrote: > > CVMs used SWIOTLB for non-trusted IO using dma_map_* APIs. This series > > will ensure that dma_alloc_* API to also allocate from SWIOTLB pools. > > Initial size of SWIOTLB pool is decided using heuristics and has been > > working with CVM usecases so far. > > > > It's better to allow SWIOTLB to scale up on demand rather than keeping > > the size fixed to avoid failures with possibly increased usage of > > SWIOTLB with dma_alloc_* APIs allocating from SWIOTLB pools. This should > > also help in future with more devices getting used from CVMs for > > non-trusted IO. > > > > Signed-off-by: Vishal Annapurve <vannapurve@google.com> > > --- > > arch/x86/Kconfig | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > > index 1566748f16c4..035c8a022c4c 100644 > > --- a/arch/x86/Kconfig > > +++ b/arch/x86/Kconfig > > @@ -884,6 +884,7 @@ config INTEL_TDX_GUEST > > select X86_MEM_ENCRYPT > > select X86_MCE > > select UNACCEPTED_MEMORY > > + select SWIOTLB_DYNAMIC > > help > > Support running as a guest under Intel TDX. Without this support, > > the guest kernel can not boot or run under TDX. > > @@ -1534,6 +1535,7 @@ config AMD_MEM_ENCRYPT > > select ARCH_HAS_CC_PLATFORM > > select X86_MEM_ENCRYPT > > select UNACCEPTED_MEMORY > > + select SWIOTLB_DYNAMIC > > help > > Say yes to enable support for the encryption of system memory. > > This requires an AMD processor that supports Secure Memory > > What this does is unconditionally enable SWIOTLB_DYNAMIC for every kernel compiled > to support memory encryption, regardless of whether it runs inside a confidential guest. > I don't think that is what you intended. >
Right, I will have to add a way to toggle this support dynamically in addition to having the support built in, based on more discussion around 2M allocations and dynamic scaling.
> Best wishes, > Jeremi > >
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