efi: use directmap to access runtime services table

Do not require switching page tables to access (static) information in
the runtime services table itself, use directmap for this. This allows
exiting early from XEN_EFI_query_capsule_capabilities,
XEN_EFI_update_capsule and XEN_EFI_query_variable_info (in case of not
supported call) without all the impact of page table switch.

Suggested-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Release-acked-by: Juergen Gross <jgross@suse.com>

diff --git a/xen/common/efi/boot.c b/xen/common/efi/boot.c
index bbe80ec02dbba9bb3a22ff1c0627f330f0b3db90..a8b6f39721fb55e9307782c5b9abb9757c56973c 100644 (file)
--- a/xen/common/efi/boot.c
+++ b/xen/common/efi/boot.c
@@ -1126,6 +1126,7 @@ static void __init efi_exit_boot(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *Syste
 
     /* Adjust pointers into EFI. */
     efi_ct = (void *)efi_ct + DIRECTMAP_VIRT_START;
+    efi_rs = (void *)efi_rs + DIRECTMAP_VIRT_START;
     efi_memmap = (void *)efi_memmap + DIRECTMAP_VIRT_START;
     efi_fw_vendor = (void *)efi_fw_vendor + DIRECTMAP_VIRT_START;
 }

diff --git a/xen/common/efi/runtime.c b/xen/common/efi/runtime.c
index ab53ebcc558bde284f91af1026ebcd7251e1e800..22fd6c9b53324b11742fd10853ecc948f1da7685 100644 (file)
--- a/xen/common/efi/runtime.c
+++ b/xen/common/efi/runtime.c
@@ -211,12 +211,7 @@ int efi_get_info(uint32_t idx, union xenpf_efi_info *info)
         break;
     case XEN_FW_EFI_RT_VERSION:
     {
-        struct efi_rs_state state = efi_rs_enter();
-
-        if ( !state.cr3 )
-            return -EOPNOTSUPP;
         info->version = efi_rs->Hdr.Revision;
-        efi_rs_leave(&state);
         break;
     }
     case XEN_FW_EFI_CONFIG_TABLE:
@@ -618,12 +613,11 @@ int efi_runtime_call(struct xenpf_efi_runtime_call *op)
             break;
         }
 
+        if ( (efi_rs->Hdr.Revision >> 16) < 2 )
+            return -EOPNOTSUPP;
         state = efi_rs_enter();
-        if ( !state.cr3 || (efi_rs->Hdr.Revision >> 16) < 2 )
-        {
-            efi_rs_leave(&state);
+        if ( !state.cr3 )
             return -EOPNOTSUPP;
-        }
         status = efi_rs->QueryVariableInfo(
             op->u.query_variable_info.attr,
             &op->u.query_variable_info.max_store_size,
@@ -637,13 +631,8 @@ int efi_runtime_call(struct xenpf_efi_runtime_call *op)
         if ( op->misc )
             return -EINVAL;
 
-        state = efi_rs_enter();
-        if ( !state.cr3 || (efi_rs->Hdr.Revision >> 16) < 2 )
-        {
-            efi_rs_leave(&state);
+        if ( (efi_rs->Hdr.Revision >> 16) < 2 )
             return -EOPNOTSUPP;
-        }
-        efi_rs_leave(&state);
         /* XXX fall through for now */
     default:
         return -ENOSYS;