When a TDX guest runs on Hyper-V, the hv_netvsc driver's netvsc_init_buf() allocates buffers using vzalloc(), and needs to share the buffers with the host OS by calling set_memory_decrypted(), which is not working for vmalloc() yet. Add the support by handling the pages one by one.

Co-developed-by: Kirill A. Shutemov kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov kirill.shutemov@linux.intel.com Reviewed-by: Michael Kelley mikelley@microsoft.com Reviewed-by: Kuppuswamy Sathyanarayanan sathyanarayanan.kuppuswamy@linux.intel.com Reviewed-by: Rick Edgecombe rick.p.edgecombe@intel.com Reviewed-by: Dave Hansen dave.hansen@linux.intel.com Acked-by: Kai Huang kai.huang@intel.com Cc: stable@vger.kernel.org # 6.6+ Signed-off-by: Dexuan Cui decui@microsoft.com ---

This is basically a repost of the second patch of the 2023 patchset: https://lwn.net/ml/linux-kernel/20230811214826.9609-3-decui@microsoft.com/

The first patch of the patchset got merged into mainline, but unluckily the second patch didn't, and I kind of lost track of it. Sorry.

Changes since the previous patchset (please refer to the link above): Added Rick's and Dave's Reviewed-by. Added Kai's Acked-by. Removeda the test "if (offset_in_page(start) != 0)" since we know the 'start' is page-aligned: see __set_memory_enc_pgtable().

Please review. Thanks! Dexuan

arch/x86/coco/tdx/tdx.c | 35 ++++++++++++++++++++++++++++------- 1 file changed, 28 insertions(+), 7 deletions(-)

diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c index c1cb90369915b..abf3cd591afd3 100644 --- a/arch/x86/coco/tdx/tdx.c +++ b/arch/x86/coco/tdx/tdx.c @@ -7,6 +7,7 @@ #include <linux/cpufeature.h> #include <linux/export.h> #include <linux/io.h> +#include <linux/mm.h> #include <asm/coco.h> #include <asm/tdx.h> #include <asm/vmx.h> @@ -778,6 +779,19 @@ static bool tdx_map_gpa(phys_addr_t start, phys_addr_t end, bool enc) return false; }

+static bool tdx_enc_status_changed_phys(phys_addr_t start, phys_addr_t end, + bool enc) +{ + if (!tdx_map_gpa(start, end, enc)) + return false; + + /* shared->private conversion requires memory to be accepted before use */ + if (enc) + return tdx_accept_memory(start, end); + + return true; +} + /* * Inform the VMM of the guest's intent for this physical page: shared with * the VMM or private to the guest. The VMM is expected to change its mapping @@ -785,15 +799,22 @@ static bool tdx_map_gpa(phys_addr_t start, phys_addr_t end, bool enc) */ static bool tdx_enc_status_changed(unsigned long vaddr, int numpages, bool enc) { - phys_addr_t start = __pa(vaddr); - phys_addr_t end = __pa(vaddr + numpages * PAGE_SIZE); + unsigned long start = vaddr; + unsigned long end = start + numpages * PAGE_SIZE; + unsigned long step = end - start; + unsigned long addr;

- if (!tdx_map_gpa(start, end, enc)) - return false; + /* Step through page-by-page for vmalloc() mappings */ + if (is_vmalloc_addr((void *)vaddr)) + step = PAGE_SIZE;

- /* shared->private conversion requires memory to be accepted before use */ - if (enc) - return tdx_accept_memory(start, end); + for (addr = start; addr < end; addr += step) { + phys_addr_t start_pa = slow_virt_to_phys((void *)addr); + phys_addr_t end_pa = start_pa + step; + + if (!tdx_enc_status_changed_phys(start_pa, end_pa, enc)) + return false; + }

return true; }