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From: "Thomas Hellström (VMware)" <thomas_os@shipmail.org>
To: linux-kernel@vger.kernel.org
Cc: pv-drivers@vmware.com, linux-graphics-maintainer@vmware.com,
	x86@kernel.org, "Thomas Hellstrom" <thellstrom@vmware.com>,
	"Dave Hansen" <dave.hansen@linux.intel.com>,
	"Andy Lutomirski" <luto@kernel.org>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Ingo Molnar" <mingo@redhat.com>,
	"Borislav Petkov" <bp@alien8.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	"Christoph Hellwig" <hch@infradead.org>,
	"Christian König" <christian.koenig@amd.com>,
	"Marek Szyprowski" <m.szyprowski@samsung.com>,
	"Tom Lendacky" <thomas.lendacky@amd.com>
Subject: [PATCH 1/2] x86: Don't let pgprot_modify() change the page encryption bit
Date: Tue, 10 Sep 2019 15:35:41 +0200	[thread overview]
Message-ID: <20190910133542.64523-2-thomas_os@shipmail.org> (raw)
In-Reply-To: <20190910133542.64523-1-thomas_os@shipmail.org>

From: Thomas Hellstrom <thellstrom@vmware.com>

When SEV or SME is enabled and active, vm_get_page_prot() typically
returns with the encryption bit set. This means that users of
pgprot_modify(, vm_get_page_prot()) (mprotect_fixup, do_mmap) typically
unintentionally sets encrypted page protection even on mmap'd coherent
memory where the mmap callback has cleared the bit. Fix this by not
allowing pgprot_modify() to change the encryption bit, similar to
how it's done for PAT bits.

Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Christian König <christian.koenig@amd.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
---
 arch/x86/include/asm/pgtable.h       | 7 +++++--
 arch/x86/include/asm/pgtable_types.h | 2 +-
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 0bc530c4eb13..1e6bb4c25334 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -624,12 +624,15 @@ static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)
 	return __pmd(val);
 }
 
-/* mprotect needs to preserve PAT bits when updating vm_page_prot */
+/*
+ * mprotect needs to preserve PAT and encryption bits when updating
+ * vm_page_prot
+ */
 #define pgprot_modify pgprot_modify
 static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
 {
 	pgprotval_t preservebits = pgprot_val(oldprot) & _PAGE_CHG_MASK;
-	pgprotval_t addbits = pgprot_val(newprot);
+	pgprotval_t addbits = pgprot_val(newprot) & ~_PAGE_CHG_MASK;
 	return __pgprot(preservebits | addbits);
 }
 
diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
index b5e49e6bac63..e13084b3d6cb 100644
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -123,7 +123,7 @@
  */
 #define _PAGE_CHG_MASK	(PTE_PFN_MASK | _PAGE_PCD | _PAGE_PWT |		\
 			 _PAGE_SPECIAL | _PAGE_ACCESSED | _PAGE_DIRTY |	\
-			 _PAGE_SOFT_DIRTY | _PAGE_DEVMAP)
+			 _PAGE_SOFT_DIRTY | _PAGE_DEVMAP | sme_me_mask)
 #define _HPAGE_CHG_MASK (_PAGE_CHG_MASK | _PAGE_PSE)
 
 /*
-- 
2.20.1


  reply	other threads:[~2019-09-10 13:36 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-10 13:35 [PATCH 0/2] Fix SEV user-space mapping of unencrypted coherent memory Thomas Hellström (VMware)
2019-09-10 13:35 ` Thomas Hellström (VMware) [this message]
2019-09-10 13:35 ` [PATCH 2/2] dma-mapping: Fix dma_pgprot() for unencrypted coherent pages Thomas Hellström (VMware)
2019-09-11  5:59 ` [PATCH 0/2] Fix SEV user-space mapping of unencrypted coherent memory Ingo Molnar
2019-09-11  8:07   ` Thomas Hellström (VMware)

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