On Tue, Apr 28, 2020 at 05:16:34PM +0200, Joerg Roedel wrote:
> @@ -302,9 +313,13 @@ void do_boot_page_fault(struct pt_regs *regs, unsigned 
> long error_code)
>        *      - User faults
>        *      - Reserved bits set
>        */
> -     if (error_code & (X86_PF_PROT | X86_PF_USER | X86_PF_RSVD)) {
> +     if (ghcb_fault ||
> +         error_code & (X86_PF_PROT | X86_PF_USER | X86_PF_RSVD)) {
>               /* Print some information for debugging */
> -             error_putstr("Unexpected page-fault:");
> +             if (ghcb_fault)
> +                     error_putstr("Page-fault on GHCB page:");
> +             else
> +                     error_putstr("Unexpected page-fault:");

You could carve out the info dumping into a separate function to
unclutter this if-statement (diff ontop):

diff --git a/arch/x86/boot/compressed/ident_map_64.c 
b/arch/x86/boot/compressed/ident_map_64.c
index d3771d455249..c1979fc0f853 100644
--- a/arch/x86/boot/compressed/ident_map_64.c
+++ b/arch/x86/boot/compressed/ident_map_64.c
@@ -296,6 +296,22 @@ int set_page_non_present(unsigned long address)
        return set_clr_page_flags(&mapping_info, address, 0, _PAGE_PRESENT);
 }
 
+static void do_pf_error(const char *msg, unsigned long error_code,
+                       unsigned long address, unsigned long ip)
+{
+       error_putstr(msg);
+
+       error_putstr("\nError Code: ");
+       error_puthex(error_code);
+       error_putstr("\nCR2: 0x");
+       error_puthex(address);
+       error_putstr("\nRIP relative to _head: 0x");
+       error_puthex(ip - (unsigned long)_head);
+       error_putstr("\n");
+
+       error("Stopping.\n");
+}
+
 void do_boot_page_fault(struct pt_regs *regs, unsigned long error_code)
 {
        unsigned long address = native_read_cr2();
@@ -309,27 +325,15 @@ void do_boot_page_fault(struct pt_regs *regs, unsigned 
long error_code)
 
        /*
         * Check for unexpected error codes. Unexpected are:
+        *      - Faults on the GHCB page due to unexpected #VCs
         *      - Faults on present pages
         *      - User faults
         *      - Reserved bits set
         */
-       if (ghcb_fault ||
-           error_code & (X86_PF_PROT | X86_PF_USER | X86_PF_RSVD)) {
-               /* Print some information for debugging */
-               if (ghcb_fault)
-                       error_putstr("Page-fault on GHCB page:");
-               else
-                       error_putstr("Unexpected page-fault:");
-               error_putstr("\nError Code: ");
-               error_puthex(error_code);
-               error_putstr("\nCR2: 0x");
-               error_puthex(address);
-               error_putstr("\nRIP relative to _head: 0x");
-               error_puthex(regs->ip - (unsigned long)_head);
-               error_putstr("\n");
-
-               error("Stopping.\n");
-       }
+       if (ghcb_fault)
+               do_pf_error("Page-fault on GHCB page:", error_code, address, 
regs->ip);
+       else if (error_code & (X86_PF_PROT | X86_PF_USER | X86_PF_RSVD))
+               do_pf_error("Unexpected page-fault:", error_code, address, 
regs->ip);
 
        /*
         * Error code is sane - now identity map the 2M region around

-- 
Regards/Gruss,
    Boris.

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