linux-kernel - [PATCH 2/2] x86/kvmclock: set_memory

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Message-Id: <20190122211758.8317-2-bauerman@linux.ibm.com>
Date:   Tue, 22 Jan 2019 19:17:58 -0200
From:   Thiago Jung Bauermann <bauerman@...ux.ibm.com>
To:     x86@...nel.org
Cc:     kvm@...r.kernel.org, iommu@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, Christoph Hellwig <hch@....de>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Robin Murphy <robin.murphy@....com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Ram Pai <linuxram@...ibm.com>,
        Thiago Jung Bauermann <bauerman@...ux.ibm.com>
Subject: [PATCH 2/2] x86/kvmclock: set_memory_decrypted() takes number of pages

From: Ram Pai <linuxram@...ibm.com>

set_memory_decrypted() expects the number of PAGE_SIZE pages to decrypt.
kvmclock_init_mem() instead passes number of bytes. This decrypts a huge
number of pages resulting in data corruption.

Fixed it.

[ bauermann: Slightly reworded commit message and added Fixes: tag. ]
Fixes: 6a1cac56f41f ("x86/kvm: Use __bss_decrypted attribute in shared variables")
Signed-off-by: Ram Pai <linuxram@...ibm.com>
Signed-off-by: Thiago Jung Bauermann <bauerman@...ux.ibm.com>
---
 arch/x86/kernel/kvmclock.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

Note: Found by code inspection. I don't have a way to test.

diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
index e811d4d1c824..b5c867dd2c8d 100644
--- a/arch/x86/kernel/kvmclock.c
+++ b/arch/x86/kernel/kvmclock.c
@@ -251,8 +251,7 @@ static void __init kvmclock_init_mem(void)
 	 * be mapped decrypted.
 	 */
 	if (sev_active()) {
-		r = set_memory_decrypted((unsigned long) hvclock_mem,
-					 1UL << order);
+		r = set_memory_decrypted((unsigned long) hvclock_mem, 1);
 		if (r) {
 			__free_pages(p, order);
 			hvclock_mem = NULL;