linux-kernel - [RFC PATCH 3/7] efi/runtime: Deal with arch_efi_call_virt

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Message-ID: <20250514174339.1834871-12-ardb+git@google.com>
Date: Wed, 14 May 2025 19:43:43 +0200
From: Ard Biesheuvel <ardb+git@...gle.com>
To: linux-efi@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	Ard Biesheuvel <ardb@...nel.org>, Will Deacon <will@...nel.org>, Mark Rutland <mark.rutland@....com>, 
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>, Peter Zijlstra <peterz@...radead.org>
Subject: [RFC PATCH 3/7] efi/runtime: Deal with arch_efi_call_virt_setup()
 returning failure

From: Ard Biesheuvel <ardb@...nel.org>

Deal with arch_efi_call_virt_setup() returning failure, by giving up and
returning an appropriate error code to the caller.

Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
---
 arch/x86/platform/uv/bios_uv.c          |  3 ++-
 drivers/firmware/efi/runtime-wrappers.c | 20 +++++++++++++-------
 include/linux/efi.h                     |  8 ++++----
 3 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/arch/x86/platform/uv/bios_uv.c b/arch/x86/platform/uv/bios_uv.c
index bf31af3d32d6..a442bbe5b1c2 100644
--- a/arch/x86/platform/uv/bios_uv.c
+++ b/arch/x86/platform/uv/bios_uv.c
@@ -32,7 +32,8 @@ static s64 __uv_bios_call(enum uv_bios_cmd which, u64 a1, u64 a2, u64 a3,
 		 */
 		return BIOS_STATUS_UNIMPLEMENTED;
 
-	ret = efi_call_virt_pointer(tab, function, (u64)which, a1, a2, a3, a4, a5);
+	ret = efi_call_virt_pointer(tab, function, BIOS_STATUS_UNIMPLEMENTED,
+				    (u64)which, a1, a2, a3, a4, a5);
 
 	return ret;
 }
diff --git a/drivers/firmware/efi/runtime-wrappers.c b/drivers/firmware/efi/runtime-wrappers.c
index 708b777857d3..82a27b414485 100644
--- a/drivers/firmware/efi/runtime-wrappers.c
+++ b/drivers/firmware/efi/runtime-wrappers.c
@@ -219,7 +219,10 @@ static void __nocfi efi_call_rts(struct work_struct *work)
 	efi_status_t status = EFI_NOT_FOUND;
 	unsigned long flags;
 
-	arch_efi_call_virt_setup();
+	if (!arch_efi_call_virt_setup()) {
+		status = EFI_NOT_READY;
+		goto out;
+	}
 	flags = efi_call_virt_save_flags();
 
 	switch (efi_rts_work.efi_rts_id) {
@@ -308,6 +311,7 @@ static void __nocfi efi_call_rts(struct work_struct *work)
 	efi_call_virt_check_flags(flags, efi_rts_work.caller);
 	arch_efi_call_virt_teardown();
 
+out:
 	efi_rts_work.status = status;
 	complete(&efi_rts_work.efi_rts_comp);
 }
@@ -444,8 +448,8 @@ virt_efi_set_variable_nb(efi_char16_t *name, efi_guid_t *vendor, u32 attr,
 	if (down_trylock(&efi_runtime_lock))
 		return EFI_NOT_READY;
 
-	status = efi_call_virt_pointer(efi.runtime, set_variable, name, vendor,
-				       attr, data_size, data);
+	status = efi_call_virt_pointer(efi.runtime, set_variable, EFI_NOT_READY,
+				       name, vendor, attr, data_size, data);
 	up(&efi_runtime_lock);
 	return status;
 }
@@ -481,9 +485,9 @@ virt_efi_query_variable_info_nb(u32 attr, u64 *storage_space,
 	if (down_trylock(&efi_runtime_lock))
 		return EFI_NOT_READY;
 
-	status = efi_call_virt_pointer(efi.runtime, query_variable_info, attr,
-				       storage_space, remaining_space,
-				       max_variable_size);
+	status = efi_call_virt_pointer(efi.runtime, query_variable_info,
+				       EFI_NOT_READY, attr, storage_space,
+				       remaining_space, max_variable_size);
 	up(&efi_runtime_lock);
 	return status;
 }
@@ -509,12 +513,14 @@ virt_efi_reset_system(int reset_type, efi_status_t status,
 		return;
 	}
 
-	arch_efi_call_virt_setup();
+	if (!arch_efi_call_virt_setup())
+		goto out;
 	efi_rts_work.efi_rts_id = EFI_RESET_SYSTEM;
 	arch_efi_call_virt(efi.runtime, reset_system, reset_type, status,
 			   data_size, data);
 	arch_efi_call_virt_teardown();
 
+out:
 	up(&efi_runtime_lock);
 }
 
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 7d63d1d75f22..13aff30be3a9 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -1179,19 +1179,19 @@ static inline void efi_check_for_embedded_firmwares(void) { }
  *    Restores the usual kernel environment once the call has returned.
  */
 
-#define efi_call_virt_pointer(p, f, args...)				\
+#define efi_call_virt_pointer(p, f, busy, args...)			\
 ({									\
-	typeof((p)->f(args)) __s;					\
+	typeof((p)->f(args)) __s = (busy);				\
 	unsigned long __flags;						\
 									\
-	arch_efi_call_virt_setup();					\
+	if (!arch_efi_call_virt_setup()) goto __out;			\
 									\
 	__flags = efi_call_virt_save_flags();				\
 	__s = arch_efi_call_virt(p, f, args);				\
 	efi_call_virt_check_flags(__flags, NULL);			\
 									\
 	arch_efi_call_virt_teardown();					\
-									\
+__out:									\
 	__s;								\
 })
 
-- 
2.49.0.1101.gccaa498523-goog