On 12/10/2021 4:09 AM, Michael Kelley (LINUX) wrote:
@@ -319,8 +320,16 @@ static void __init ms_hyperv_init_platform(void) pr_info("Hyper-V: Isolation Config: Group A 0x%x, Group B 0x%x\n", ms_hyperv.isolation_config_a, ms_hyperv.isolation_config_b); - if (hv_get_isolation_type() == HV_ISOLATION_TYPE_SNP) + if (hv_get_isolation_type() == HV_ISOLATION_TYPE_SNP) { static_branch_enable(&isolation_type_snp); + swiotlb_unencrypted_base = ms_hyperv.shared_gpa_boundary; + } + + /* + * Enable swiotlb force mode in Isolation VM to + * use swiotlb bounce buffer for dma transaction. + */ + swiotlb_force = SWIOTLB_FORCE;I'm good with this approach that directly updates the swiotlb settings here rather than in IOMMU initialization code. It's a lot more straightforward. However, there's an issue if building for X86_32 without PAE, in that the swiotlb module may not be built, resulting in compile and link errors. The swiotlb.h file needs to be updated to provide a stub function for swiotlb_update_mem_attributes(). swiotlb_unencrypted_base probably needs wrapper functions to get/set it, which can be stubs when CONFIG_SWIOTLB is not set. swiotlb_force is a bit of a mess in that it already has a stub definition that assumes it will only be read, and not set. A bit of thinking will be needed to sort that out.
It's ok to fix the issue via selecting swiotlb when CONFIG_HYPERV is set?
} if (hv_max_functions_eax >= HYPERV_CPUID_NESTED_FEATURES) { diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h index b823311eac79..1f037e114dc8 100644 --- a/include/linux/hyperv.h +++ b/include/linux/hyperv.h @@ -1726,6 +1726,14 @@ int hyperv_write_cfg_blk(struct pci_dev *dev, void *buf, unsigned int len, int hyperv_reg_block_invalidate(struct pci_dev *dev, void *context, void (*block_invalidate)(void *context, u64 block_mask)); +#if IS_ENABLED(CONFIG_HYPERV) +int __init hyperv_swiotlb_detect(void); +#else +static inline int __init hyperv_swiotlb_detect(void) +{ + return 0; +} +#endifI don't think hyperv_swiotlb_detect() is used any longer, so this change should be dropped.
Yes, will update.
