Messages in this thread | | | Date | Mon, 30 Oct 2023 11:51:06 +0530 | Subject | Re: [PATCH 0/3] Introduce DMA APIs to allocate and free TEE shared memory | From | "NK, JESHWANTHKUMAR" <> |
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Hi Tom,
On 26-Oct-23 8:23 PM, Tom Lendacky wrote: > On 10/26/23 05:30, NK, JESHWANTHKUMAR wrote: >> >> On 25-Oct-23 7:01 PM, Sumit Garg wrote: >>> Hi Jeshwank, >>> >>> On Wed, 25 Oct 2023 at 12:27, jeshwank <JESHWANTHKUMAR.NK@amd.com> >>> wrote: >>>> From: Jeshwanth Kumar N K <JESHWANTHKUMAR.NK@amd.com> >>>> >>>> At present, the shared memory for TEE ring buffer, command buffer and >>>> data buffer is allocated using get_free_pages(). The driver shares the >>>> physical address of these buffers with PSP so that it can be mapped by >>>> the Trusted OS. >>>> >>>> In this patch series we have replaced get_free_pages() with >>>> dma_alloc_coherent() to allocate shared memory to cleanup the existing >>>> allocation method. >>> Thanks for putting this together but I can't find the reasoning behind >>> this change neither in this commit message and nor in the patch >>> descriptions. Care to explain why? >>> >>> -Sumit >> Hi Sumit, >> >> We see that there is an advantage in using dma_alloc_coherent() over >> get_free_pages(). The dma-ops associated with PSP PCIe device can be >> overridden. This capability will be helpful when we enable >> virtualization support. We plan to post a virtualization related >> patch in future. > > To be specific, you are referring to Xen virtualization support, > correct? Because I don't see how this works in a Qemu/KVM environment > where you would get a GPA and not an SPA.
The patch is not specific to Xen. We have verified it in Qemu/KVM and Xen PV mode. Support for Xen PVH mode will be added as a separate patch.
> > If that is the case, you should clearly specify that. Also, this looks > like it should be introduced with the virtualization support that you > submit in the future and not before.
I will update the commit message in the next version of the patch series to include these details.
> Thanks, > Tom > >> >> Regards, >> >> Jeshwanth >> >>> >>>> Rijo Thomas (3): >>>> crypto: ccp - Add function to allocate and free memory using DMA >>>> APIs >>>> crypto: ccp - Use psp_tee_alloc_buffer() and psp_tee_free_buffer() >>>> tee: amdtee: Use psp_tee_alloc_buffer() and psp_tee_free_buffer() >>>> >>>> drivers/crypto/ccp/psp-dev.c | 3 + >>>> drivers/crypto/ccp/tee-dev.c | 119 >>>> ++++++++++++++++++---------- >>>> drivers/crypto/ccp/tee-dev.h | 11 +-- >>>> drivers/tee/amdtee/amdtee_private.h | 18 ++--- >>>> drivers/tee/amdtee/call.c | 74 ++++++++--------- >>>> drivers/tee/amdtee/core.c | 72 ++++++++++------- >>>> drivers/tee/amdtee/shm_pool.c | 21 ++--- >>>> include/linux/psp-tee.h | 47 +++++++++++ >>>> 8 files changed, 221 insertions(+), 144 deletions(-) >>>> >>>> -- >>>> 2.25.1 >>>>
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