Re: [PATCH] x86/tdx: Support vmalloc() for tdx_enc_status_changed()

[Kirill A. Shutemov]

On Mon, May 20, 2024 at 07:12:38PM -0700, Dexuan Cui wrote:
> @@ -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;
>  }

This patch collied with kexec changes. tdx_kexec_finish() calls
tdx_enc_status_changed() after clearing pte, so slow_virt_to_phys()
crashes on in.

Daxuan, could you check if the fixup below works for you on vmalloc
addresses?

diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c
index ef8ec2425998..5e455c883bcc 100644
--- a/arch/x86/coco/tdx/tdx.c
+++ b/arch/x86/coco/tdx/tdx.c
@@ -813,8 +813,15 @@ static bool tdx_enc_status_changed(unsigned long vaddr, 
int numpages, bool enc)
                step = PAGE_SIZE;
 
        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;
+               phys_addr_t start_pa;
+               phys_addr_t end_pa;
+
+               if (virt_addr_valid(addr))
+                       start_pa = __pa(addr);
+               else
+                       start_pa = slow_virt_to_phys((void *)addr);
+
+               end_pa = start_pa + step;
 
                if (!tdx_enc_status_changed_phys(start_pa, end_pa, enc))
                        return false;
-- 
  Kiryl Shutsemau / Kirill A. Shutemov