Commit f5ed7775 authored by Martin Radev's avatar Martin Radev Committed by Borislav Petkov
Browse files

x86/sev-es: Check required CPU features for SEV-ES 



Make sure the machine supports RDRAND, otherwise there is no trusted
source of randomness in the system.

To also check this in the pre-decompression stage, make has_cpuflag()
not depend on CONFIG_RANDOMIZE_BASE anymore.

Signed-off-by: default avatarMartin Radev <martin.b.radev@gmail.com>
Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/20200907131613.12703-73-joro@8bytes.org
parent 39336f4f

arch/x86/boot/compressed/cpuflags.c

+0 −4
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

#ifdef CONFIG_RANDOMIZE_BASE



#include "../cpuflags.c"



bool has_cpuflag(int flag)
@@ -9,5 +7,3 @@ bool has_cpuflag(int flag) 


	return test_bit(flag, cpu.flags);

}
 


#endif

arch/x86/boot/compressed/misc.h

+3 −2
Original line number Diff line number Diff line
@@ -85,8 +85,6 @@ void choose_random_location(unsigned long input, 
			    unsigned long *output,

			    unsigned long output_size,

			    unsigned long *virt_addr);

/* cpuflags.c */

bool has_cpuflag(int flag);

#else

static inline void choose_random_location(unsigned long input,

					  unsigned long input_size,
@@ -97,6 +95,9 @@ static inline void choose_random_location(unsigned long input, 
}

#endif



/* cpuflags.c */

bool has_cpuflag(int flag);



#ifdef CONFIG_X86_64

extern int set_page_decrypted(unsigned long address);

extern int set_page_encrypted(unsigned long address);

arch/x86/boot/compressed/sev-es.c

+3 −0
Original line number Diff line number Diff line
@@ -145,6 +145,9 @@ void sev_es_shutdown_ghcb(void) 
	if (!boot_ghcb)

		return;



	if (!sev_es_check_cpu_features())

		error("SEV-ES CPU Features missing.");



	/*

	 * GHCB Page must be flushed from the cache and mapped encrypted again.

	 * Otherwise the running kernel will see strange cache effects when

arch/x86/kernel/sev-es-shared.c

+15 −0
Original line number Diff line number Diff line
@@ -9,6 +9,21 @@ 
 * and is included directly into both code-bases.

 */



#ifndef __BOOT_COMPRESSED

#define error(v)	pr_err(v)

#define has_cpuflag(f)	boot_cpu_has(f)

#endif



static bool __init sev_es_check_cpu_features(void)

{

	if (!has_cpuflag(X86_FEATURE_RDRAND)) {

		error("RDRAND instruction not supported - no trusted source of randomness available\n");

		return false;

	}



	return true;

}



static void sev_es_terminate(unsigned int reason)

{

	u64 val = GHCB_SEV_TERMINATE;

arch/x86/kernel/sev-es.c

+3 −0
Original line number Diff line number Diff line
@@ -665,6 +665,9 @@ void __init sev_es_init_vc_handling(void) 
	if (!sev_es_active())

		return;



	if (!sev_es_check_cpu_features())

		panic("SEV-ES CPU Features missing");



	/* Enable SEV-ES special handling */

	static_branch_enable(&sev_es_enable_key);

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