Hi Michael, On 3/4/22 10:12 AM, Michael Kelley (LINUX) wrote: > From: Christoph Hellwig <hch@xxxxxx> Sent: Tuesday, March 1, 2022 2:53 AM >> >> Power SVM wants to allocate a swiotlb buffer that is not restricted to low memory for >> the trusted hypervisor scheme. Consolidate the support for this into the swiotlb_init >> interface by adding a new flag. > > Hyper-V Isolated VMs want to do the same thing of not restricting the swiotlb > buffer to low memory. That's what Tianyu Lan's patch set[1] is proposing. > Hyper-V synthetic devices have no DMA addressing limitations, and the > likelihood of using a PCI pass-thru device with addressing limitations in an > Isolated VM seems vanishingly small. > > So could use of the SWIOTLB_ANY flag be generalized? Let Hyper-V init > code set the flag before swiotlb_init() is called. Or provide a CONFIG > variable that Hyper-V Isolated VMs could set. I used to send 64-bit swiotlb, while at that time people thought it was the same as Restricted DMA patchset. https://lore.kernel.org/all/20210203233709.19819-1-dongli.zhang@xxxxxxxxxx/ However, I do not think Restricted DMA patchset is going to supports 64-bit (or high memory) DMA. Is this what you are looking for? Dongli Zhang > > Michael > > [1] https://urldefense.com/v3/__https://lore.kernel.org/lkml/20220209122302.213882-1-ltykernel@xxxxxxxxx/__;!!ACWV5N9M2RV99hQ!fUx4fMgdQIrqJDDy-pbv9xMeyHX0rC6iN8176LWjylI2_lsjy03gysm0-lAbV1Yb7_g$ > >> >> Signed-off-by: Christoph Hellwig <hch@xxxxxx> >> --- >> arch/powerpc/include/asm/svm.h | 4 ---- >> arch/powerpc/include/asm/swiotlb.h | 1 + >> arch/powerpc/kernel/dma-swiotlb.c | 1 + >> arch/powerpc/mm/mem.c | 5 +---- >> arch/powerpc/platforms/pseries/svm.c | 26 +------------------------- >> include/linux/swiotlb.h | 1 + >> kernel/dma/swiotlb.c | 9 +++++++-- >> 7 files changed, 12 insertions(+), 35 deletions(-) >> >> diff --git a/arch/powerpc/include/asm/svm.h b/arch/powerpc/include/asm/svm.h >> index 7546402d796af..85580b30aba48 100644 >> --- a/arch/powerpc/include/asm/svm.h >> +++ b/arch/powerpc/include/asm/svm.h >> @@ -15,8 +15,6 @@ static inline bool is_secure_guest(void) >> return mfmsr() & MSR_S; >> } >> >> -void __init svm_swiotlb_init(void); >> - >> void dtl_cache_ctor(void *addr); >> #define get_dtl_cache_ctor() (is_secure_guest() ? dtl_cache_ctor : NULL) >> >> @@ -27,8 +25,6 @@ static inline bool is_secure_guest(void) >> return false; >> } >> >> -static inline void svm_swiotlb_init(void) {} >> - >> #define get_dtl_cache_ctor() NULL >> >> #endif /* CONFIG_PPC_SVM */ >> diff --git a/arch/powerpc/include/asm/swiotlb.h >> b/arch/powerpc/include/asm/swiotlb.h >> index 3c1a1cd161286..4203b5e0a88ed 100644 >> --- a/arch/powerpc/include/asm/swiotlb.h >> +++ b/arch/powerpc/include/asm/swiotlb.h >> @@ -9,6 +9,7 @@ >> #include <linux/swiotlb.h> >> >> extern unsigned int ppc_swiotlb_enable; >> +extern unsigned int ppc_swiotlb_flags; >> >> #ifdef CONFIG_SWIOTLB >> void swiotlb_detect_4g(void); >> diff --git a/arch/powerpc/kernel/dma-swiotlb.c b/arch/powerpc/kernel/dma- >> swiotlb.c >> index fc7816126a401..ba256c37bcc0f 100644 >> --- a/arch/powerpc/kernel/dma-swiotlb.c >> +++ b/arch/powerpc/kernel/dma-swiotlb.c >> @@ -10,6 +10,7 @@ >> #include <asm/swiotlb.h> >> >> unsigned int ppc_swiotlb_enable; >> +unsigned int ppc_swiotlb_flags; >> >> void __init swiotlb_detect_4g(void) >> { >> diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c index >> e1519e2edc656..a4d65418c30a9 100644 >> --- a/arch/powerpc/mm/mem.c >> +++ b/arch/powerpc/mm/mem.c >> @@ -249,10 +249,7 @@ void __init mem_init(void) >> * back to to-down. >> */ >> memblock_set_bottom_up(true); >> - if (is_secure_guest()) >> - svm_swiotlb_init(); >> - else >> - swiotlb_init(ppc_swiotlb_enable, 0); >> + swiotlb_init(ppc_swiotlb_enable, ppc_swiotlb_flags); >> #endif >> >> high_memory = (void *) __va(max_low_pfn * PAGE_SIZE); diff --git >> a/arch/powerpc/platforms/pseries/svm.c b/arch/powerpc/platforms/pseries/svm.c >> index c5228f4969eb2..3b4045d508ec8 100644 >> --- a/arch/powerpc/platforms/pseries/svm.c >> +++ b/arch/powerpc/platforms/pseries/svm.c >> @@ -28,7 +28,7 @@ static int __init init_svm(void) >> * need to use the SWIOTLB buffer for DMA even if dma_capable() says >> * otherwise. >> */ >> - swiotlb_force = SWIOTLB_FORCE; >> + ppc_swiotlb_flags |= SWIOTLB_ANY | SWIOTLB_FORCE; >> >> /* Share the SWIOTLB buffer with the host. */ >> swiotlb_update_mem_attributes(); >> @@ -37,30 +37,6 @@ static int __init init_svm(void) } machine_early_initcall(pseries, >> init_svm); >> >> -/* >> - * Initialize SWIOTLB. Essentially the same as swiotlb_init(), except that it >> - * can allocate the buffer anywhere in memory. Since the hypervisor doesn't have >> - * any addressing limitation, we don't need to allocate it in low addresses. >> - */ >> -void __init svm_swiotlb_init(void) >> -{ >> - unsigned char *vstart; >> - unsigned long bytes, io_tlb_nslabs; >> - >> - io_tlb_nslabs = (swiotlb_size_or_default() >> IO_TLB_SHIFT); >> - io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE); >> - >> - bytes = io_tlb_nslabs << IO_TLB_SHIFT; >> - >> - vstart = memblock_alloc(PAGE_ALIGN(bytes), PAGE_SIZE); >> - if (vstart && !swiotlb_init_with_tbl(vstart, io_tlb_nslabs, false)) >> - return; >> - >> - >> - memblock_free(vstart, PAGE_ALIGN(io_tlb_nslabs << IO_TLB_SHIFT)); >> - panic("SVM: Cannot allocate SWIOTLB buffer"); >> -} >> - >> int set_memory_encrypted(unsigned long addr, int numpages) { >> if (!cc_platform_has(CC_ATTR_MEM_ENCRYPT)) >> diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h index >> dcecf953f7997..ee655f2e4d28b 100644 >> --- a/include/linux/swiotlb.h >> +++ b/include/linux/swiotlb.h >> @@ -15,6 +15,7 @@ struct scatterlist; >> >> #define SWIOTLB_VERBOSE (1 << 0) /* verbose initialization */ >> #define SWIOTLB_FORCE (1 << 1) /* force bounce buffering */ >> +#define SWIOTLB_ANY (1 << 2) /* allow any memory for the buffer */ >> >> /* >> * Maximum allowable number of contiguous slabs to map, diff --git >> a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index 1a40c71c4d51a..77cf73dc20a78 >> 100644 >> --- a/kernel/dma/swiotlb.c >> +++ b/kernel/dma/swiotlb.c >> @@ -275,8 +275,13 @@ void __init swiotlb_init(bool addressing_limit, unsigned int >> flags) >> if (swiotlb_force_disable) >> return; >> >> - /* Get IO TLB memory from the low pages */ >> - tlb = memblock_alloc_low(bytes, PAGE_SIZE); >> + /* >> + * By default allocate the bonuce buffer memory from low memory. >> + */ >> + if (flags & SWIOTLB_ANY) >> + tlb = memblock_alloc(bytes, PAGE_SIZE); >> + else >> + tlb = memblock_alloc_low(bytes, PAGE_SIZE); >> if (!tlb) >> goto fail; >> if (swiotlb_init_with_tbl(tlb, default_nslabs, flags)) >> -- >> 2.30.2 > >
