| Message ID | 20210414144945.3460554-10-ltykernel@gmail.com (mailing list archive) |
|---|---|
| State | RFC |
| Headers | show |
| Series | x86/Hyper-V: Add Hyper-V Isolation VM support | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Guessing tree name failed - patch did not apply |
On Wed, Apr 14, 2021 at 10:49:42AM -0400, Tianyu Lan wrote: > From: Tianyu Lan <Tianyu.Lan@microsoft.com> > > For Hyper-V isolation VM with AMD SEV SNP, the bounce buffer(shared memory) > needs to be accessed via extra address space(e.g address above bit39). > Hyper-V code may remap extra address space outside of swiotlb. swiotlb_bounce() May? Isn't this a MUST in this case? > needs to use remap virtual address to copy data from/to bounce buffer. Add > new interface swiotlb_set_bounce_remap() to do that. I am bit lost - why can't you use the swiotlb_init and pass in your DMA pool that is already above bit 39? > > Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com> > --- > include/linux/swiotlb.h | 5 +++++ > kernel/dma/swiotlb.c | 13 ++++++++++++- > 2 files changed, 17 insertions(+), 1 deletion(-) > > diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h > index d9c9fc9ca5d2..3ccd08116683 100644 > --- a/include/linux/swiotlb.h > +++ b/include/linux/swiotlb.h > @@ -82,8 +82,13 @@ unsigned int swiotlb_max_segment(void); > size_t swiotlb_max_mapping_size(struct device *dev); > bool is_swiotlb_active(void); > void __init swiotlb_adjust_size(unsigned long new_size); > +void swiotlb_set_bounce_remap(unsigned char *vaddr); > #else > #define swiotlb_force SWIOTLB_NO_FORCE > +static inline void swiotlb_set_bounce_remap(unsigned char *vaddr) > +{ > +} > + > static inline bool is_swiotlb_buffer(phys_addr_t paddr) > { > return false; > diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c > index 7c42df6e6100..5fd2db6aa149 100644 > --- a/kernel/dma/swiotlb.c > +++ b/kernel/dma/swiotlb.c > @@ -94,6 +94,7 @@ static unsigned int io_tlb_index; > * not be bounced (unless SWIOTLB_FORCE is set). > */ > static unsigned int max_segment; > +static unsigned char *swiotlb_bounce_remap_addr; > > /* > * We need to save away the original address corresponding to a mapped entry > @@ -421,6 +422,11 @@ void __init swiotlb_exit(void) > swiotlb_cleanup(); > } > > +void swiotlb_set_bounce_remap(unsigned char *vaddr) > +{ > + swiotlb_bounce_remap_addr = vaddr; > +} > + > /* > * Bounce: copy the swiotlb buffer from or back to the original dma location > */ > @@ -428,7 +434,12 @@ static void swiotlb_bounce(phys_addr_t orig_addr, phys_addr_t tlb_addr, > size_t size, enum dma_data_direction dir) > { > unsigned long pfn = PFN_DOWN(orig_addr); > - unsigned char *vaddr = phys_to_virt(tlb_addr); > + unsigned char *vaddr; > + > + if (swiotlb_bounce_remap_addr) > + vaddr = swiotlb_bounce_remap_addr + tlb_addr - io_tlb_start; > + else > + vaddr = phys_to_virt(tlb_addr); > > if (PageHighMem(pfn_to_page(pfn))) { > /* The buffer does not have a mapping. Map it in and copy */ > -- > 2.25.1 >
diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h index d9c9fc9ca5d2..3ccd08116683 100644 --- a/include/linux/swiotlb.h +++ b/include/linux/swiotlb.h @@ -82,8 +82,13 @@ unsigned int swiotlb_max_segment(void); size_t swiotlb_max_mapping_size(struct device *dev); bool is_swiotlb_active(void); void __init swiotlb_adjust_size(unsigned long new_size); +void swiotlb_set_bounce_remap(unsigned char *vaddr); #else #define swiotlb_force SWIOTLB_NO_FORCE +static inline void swiotlb_set_bounce_remap(unsigned char *vaddr) +{ +} + static inline bool is_swiotlb_buffer(phys_addr_t paddr) { return false; diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index 7c42df6e6100..5fd2db6aa149 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -94,6 +94,7 @@ static unsigned int io_tlb_index; * not be bounced (unless SWIOTLB_FORCE is set). */ static unsigned int max_segment; +static unsigned char *swiotlb_bounce_remap_addr; /* * We need to save away the original address corresponding to a mapped entry @@ -421,6 +422,11 @@ void __init swiotlb_exit(void) swiotlb_cleanup(); } +void swiotlb_set_bounce_remap(unsigned char *vaddr) +{ + swiotlb_bounce_remap_addr = vaddr; +} + /* * Bounce: copy the swiotlb buffer from or back to the original dma location */ @@ -428,7 +434,12 @@ static void swiotlb_bounce(phys_addr_t orig_addr, phys_addr_t tlb_addr, size_t size, enum dma_data_direction dir) { unsigned long pfn = PFN_DOWN(orig_addr); - unsigned char *vaddr = phys_to_virt(tlb_addr); + unsigned char *vaddr; + + if (swiotlb_bounce_remap_addr) + vaddr = swiotlb_bounce_remap_addr + tlb_addr - io_tlb_start; + else + vaddr = phys_to_virt(tlb_addr); if (PageHighMem(pfn_to_page(pfn))) { /* The buffer does not have a mapping. Map it in and copy */