On Mon, Feb 28, 2022 at 02:53:39AM +0000, Michael Kelley (LINUX) wrote: > From: Christoph Hellwig <hch@xxxxxx> Sent: Sunday, February 27, 2022 6:31 AM > > > > Pass a bool to pass if swiotlb needs to be enabled based on the > > addressing needs and replace the verbose argument with a set of > > flags, including one to force enable bounce buffering. > > > > Note that this patch removes the possibility to force xen-swiotlb > > use using swiotlb=force on the command line on x86 (arm and arm64 > > never supported that), but this interface will be restored shortly. > > > > Signed-off-by: Christoph Hellwig <hch@xxxxxx> > > --- > > arch/arm/mm/init.c | 6 +---- > > arch/arm64/mm/init.c | 6 +---- > > arch/ia64/mm/init.c | 4 +-- > > arch/mips/cavium-octeon/dma-octeon.c | 2 +- > > arch/mips/loongson64/dma.c | 2 +- > > arch/mips/sibyte/common/dma.c | 2 +- > > arch/powerpc/include/asm/swiotlb.h | 1 + > > arch/powerpc/mm/mem.c | 3 ++- > > arch/powerpc/platforms/pseries/setup.c | 3 --- > > arch/riscv/mm/init.c | 8 +----- > > arch/s390/mm/init.c | 3 +-- > > arch/x86/kernel/cpu/mshyperv.c | 8 ------ > > arch/x86/kernel/pci-dma.c | 15 ++++++----- > > arch/x86/mm/mem_encrypt_amd.c | 3 --- > > drivers/xen/swiotlb-xen.c | 4 +-- > > include/linux/swiotlb.h | 15 ++++++----- > > include/trace/events/swiotlb.h | 29 ++++++++------------- > > kernel/dma/swiotlb.c | 35 ++++++++++++++------------ > > 18 files changed, 56 insertions(+), 93 deletions(-) > > [snip] > > > > > diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c > > index 5a99f993e6392..568274917f1cd 100644 > > --- a/arch/x86/kernel/cpu/mshyperv.c > > +++ b/arch/x86/kernel/cpu/mshyperv.c > > @@ -336,14 +336,6 @@ static void __init ms_hyperv_init_platform(void) > > swiotlb_unencrypted_base = ms_hyperv.shared_gpa_boundary; > > #endif > > } > > - > > -#ifdef CONFIG_SWIOTLB > > - /* > > - * Enable swiotlb force mode in Isolation VM to > > - * use swiotlb bounce buffer for dma transaction. > > - */ > > - swiotlb_force = SWIOTLB_FORCE; > > -#endif > > With this code removed, it's not clear to me what forces the use of the > swiotlb in a Hyper-V isolated VM. The code in pci_swiotlb_detect_4g() doesn't > catch this case because cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT) > returns "false" in a Hyper-V guest. In the Hyper-V guest, it's only > cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) that returns "true". I'm > looking more closely at the meaning of the CC_ATTR_* values, and it may > be that Hyper-V should also return "true" for CC_ATTR_MEM_ENCRYPT, > but I don't think CC_ATTR_HOST_MEM_ENCRYPT should return "true". Ok, I assumed that CC_ATTR_HOST_MEM_ENCRYPT returned true in this case. I guess we just need to check for CC_ATTR_GUEST_MEM_ENCRYPT as well there?
