This is a note to let you know that I've just added the patch titled powerpc/pseries/svm: Allocate SWIOTLB buffer anywhere in memory to the 5.8-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: powerpc-pseries-svm-allocate-swiotlb-buffer-anywhere.patch and it can be found in the queue-5.8 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit f5d2008e4ed654938c74316e22bb06f9b757a9d8 Author: Thiago Jung Bauermann <bauerman@xxxxxxxxxxxxx> Date: Tue Aug 18 19:11:26 2020 -0300 powerpc/pseries/svm: Allocate SWIOTLB buffer anywhere in memory [ Upstream commit eae9eec476d13fad9af6da1f44a054ee02b7b161 ] POWER secure guests (i.e., guests which use the Protected Execution Facility) need to use SWIOTLB to be able to do I/O with the hypervisor, but they don't need the SWIOTLB memory to be in low addresses since the hypervisor doesn't have any addressing limitation. This solves a SWIOTLB initialization problem we are seeing in secure guests with 128 GB of RAM: they are configured with 4 GB of crashkernel reserved memory, which leaves no space for SWIOTLB in low addresses. To do this, we use mostly the same code as swiotlb_init(), but allocate the buffer using memblock_alloc() instead of memblock_alloc_low(). Fixes: 2efbc58f157a ("powerpc/pseries/svm: Force SWIOTLB for secure guests") Signed-off-by: Thiago Jung Bauermann <bauerman@xxxxxxxxxxxxx> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20200818221126.391073-1-bauerman@xxxxxxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/arch/powerpc/include/asm/svm.h b/arch/powerpc/include/asm/svm.h index 85580b30aba48..7546402d796af 100644 --- a/arch/powerpc/include/asm/svm.h +++ b/arch/powerpc/include/asm/svm.h @@ -15,6 +15,8 @@ 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) @@ -25,6 +27,8 @@ 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/mm/mem.c b/arch/powerpc/mm/mem.c index c2c11eb8dcfca..0f21bcb16405a 100644 --- a/arch/powerpc/mm/mem.c +++ b/arch/powerpc/mm/mem.c @@ -50,6 +50,7 @@ #include <asm/swiotlb.h> #include <asm/rtas.h> #include <asm/kasan.h> +#include <asm/svm.h> #include <mm/mmu_decl.h> @@ -290,7 +291,10 @@ void __init mem_init(void) * back to to-down. */ memblock_set_bottom_up(true); - swiotlb_init(0); + if (is_secure_guest()) + svm_swiotlb_init(); + else + swiotlb_init(0); #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 40c0637203d5b..81085eb8f2255 100644 --- a/arch/powerpc/platforms/pseries/svm.c +++ b/arch/powerpc/platforms/pseries/svm.c @@ -7,6 +7,7 @@ */ #include <linux/mm.h> +#include <linux/memblock.h> #include <asm/machdep.h> #include <asm/svm.h> #include <asm/swiotlb.h> @@ -34,6 +35,31 @@ 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; + + if (io_tlb_start) + memblock_free_early(io_tlb_start, + PAGE_ALIGN(io_tlb_nslabs << IO_TLB_SHIFT)); + panic("SVM: Cannot allocate SWIOTLB buffer"); +} + int set_memory_encrypted(unsigned long addr, int numpages) { if (!PAGE_ALIGNED(addr))