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Message-ID: <163898133021.11128.8153755611044440687.tip-bot2@tip-bot2>
Date: Wed, 08 Dec 2021 16:35:30 -0000
From: "tip-bot2 for Kuppuswamy Sathyanarayanan" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Tom Lendacky <thomas.lendacky@....com>,
Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@...ux.intel.com>,
"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
Borislav Petkov <bp@...e.de>, Tony Luck <tony.luck@...el.com>,
x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [tip: x86/sev] x86/sev: Use CC_ATTR attribute to generalize string I/O unroll
The following commit has been merged into the x86/sev branch of tip:
Commit-ID: 8260b9820f7050461b8969305bbd8cb5654f0c74
Gitweb: https://git.kernel.org/tip/8260b9820f7050461b8969305bbd8cb5654f0c74
Author: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
AuthorDate: Mon, 06 Dec 2021 16:55:03 +03:00
Committer: Borislav Petkov <bp@...e.de>
CommitterDate: Wed, 08 Dec 2021 16:49:42 +01:00
x86/sev: Use CC_ATTR attribute to generalize string I/O unroll
INS/OUTS are not supported in TDX guests and cause #UD. Kernel has to
avoid them when running in TDX guest. To support existing usage, string
I/O operations are unrolled using IN/OUT instructions.
AMD SEV platform implements this support by adding unroll
logic in ins#bwl()/outs#bwl() macros with SEV-specific checks.
Since TDX VM guests will also need similar support, use
CC_ATTR_GUEST_UNROLL_STRING_IO and generic cc_platform_has() API to
implement it.
String I/O helpers were the last users of sev_key_active() interface and
sev_enable_key static key. Remove them.
[ bp: Move comment too and do not delete it. ]
Suggested-by: Tom Lendacky <thomas.lendacky@....com>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Reviewed-by: Tony Luck <tony.luck@...el.com>
Reviewed-by: Tom Lendacky <thomas.lendacky@....com>
Tested-by: Tom Lendacky <thomas.lendacky@....com>
Link: https://lkml.kernel.org/r/20211206135505.75045-2-kirill.shutemov@linux.intel.com
---
arch/x86/include/asm/io.h | 20 +++-----------------
arch/x86/kernel/cc_platform.c | 8 ++++++++
arch/x86/mm/mem_encrypt.c | 10 ----------
include/linux/cc_platform.h | 11 +++++++++++
4 files changed, 22 insertions(+), 27 deletions(-)
diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
index 5c6a4af..f6d91ec 100644
--- a/arch/x86/include/asm/io.h
+++ b/arch/x86/include/asm/io.h
@@ -40,6 +40,7 @@
#include <linux/string.h>
#include <linux/compiler.h>
+#include <linux/cc_platform.h>
#include <asm/page.h>
#include <asm/early_ioremap.h>
#include <asm/pgtable_types.h>
@@ -256,21 +257,6 @@ static inline void slow_down_io(void)
#endif
-#ifdef CONFIG_AMD_MEM_ENCRYPT
-#include <linux/jump_label.h>
-
-extern struct static_key_false sev_enable_key;
-static inline bool sev_key_active(void)
-{
- return static_branch_unlikely(&sev_enable_key);
-}
-
-#else /* !CONFIG_AMD_MEM_ENCRYPT */
-
-static inline bool sev_key_active(void) { return false; }
-
-#endif /* CONFIG_AMD_MEM_ENCRYPT */
-
#define BUILDIO(bwl, bw, type) \
static inline void out##bwl(unsigned type value, int port) \
{ \
@@ -301,7 +287,7 @@ static inline unsigned type in##bwl##_p(int port) \
\
static inline void outs##bwl(int port, const void *addr, unsigned long count) \
{ \
- if (sev_key_active()) { \
+ if (cc_platform_has(CC_ATTR_GUEST_UNROLL_STRING_IO)) { \
unsigned type *value = (unsigned type *)addr; \
while (count) { \
out##bwl(*value, port); \
@@ -317,7 +303,7 @@ static inline void outs##bwl(int port, const void *addr, unsigned long count) \
\
static inline void ins##bwl(int port, void *addr, unsigned long count) \
{ \
- if (sev_key_active()) { \
+ if (cc_platform_has(CC_ATTR_GUEST_UNROLL_STRING_IO)) { \
unsigned type *value = (unsigned type *)addr; \
while (count) { \
*value = in##bwl(port); \
diff --git a/arch/x86/kernel/cc_platform.c b/arch/x86/kernel/cc_platform.c
index 03bb2f3..8a25b1c 100644
--- a/arch/x86/kernel/cc_platform.c
+++ b/arch/x86/kernel/cc_platform.c
@@ -50,6 +50,14 @@ static bool amd_cc_platform_has(enum cc_attr attr)
case CC_ATTR_GUEST_STATE_ENCRYPT:
return sev_status & MSR_AMD64_SEV_ES_ENABLED;
+ /*
+ * With SEV, the rep string I/O instructions need to be unrolled
+ * but SEV-ES supports them through the #VC handler.
+ */
+ case CC_ATTR_GUEST_UNROLL_STRING_IO:
+ return (sev_status & MSR_AMD64_SEV_ENABLED) &&
+ !(sev_status & MSR_AMD64_SEV_ES_ENABLED);
+
default:
return false;
}
diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
index 3548730..b520021 100644
--- a/arch/x86/mm/mem_encrypt.c
+++ b/arch/x86/mm/mem_encrypt.c
@@ -43,8 +43,6 @@ u64 sme_me_mask __section(".data") = 0;
u64 sev_status __section(".data") = 0;
u64 sev_check_data __section(".data") = 0;
EXPORT_SYMBOL(sme_me_mask);
-DEFINE_STATIC_KEY_FALSE(sev_enable_key);
-EXPORT_SYMBOL_GPL(sev_enable_key);
/* Buffer used for early in-place encryption by BSP, no locking needed */
static char sme_early_buffer[PAGE_SIZE] __initdata __aligned(PAGE_SIZE);
@@ -499,14 +497,6 @@ void __init mem_encrypt_init(void)
/* Call into SWIOTLB to update the SWIOTLB DMA buffers */
swiotlb_update_mem_attributes();
- /*
- * With SEV, we need to unroll the rep string I/O instructions,
- * but SEV-ES supports them through the #VC handler.
- */
- if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) &&
- !cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT))
- static_branch_enable(&sev_enable_key);
-
print_mem_encrypt_feature_info();
}
diff --git a/include/linux/cc_platform.h b/include/linux/cc_platform.h
index a075b70..efd8205 100644
--- a/include/linux/cc_platform.h
+++ b/include/linux/cc_platform.h
@@ -61,6 +61,17 @@ enum cc_attr {
* Examples include SEV-ES.
*/
CC_ATTR_GUEST_STATE_ENCRYPT,
+
+ /**
+ * @CC_ATTR_GUEST_UNROLL_STRING_IO: String I/O is implemented with
+ * IN/OUT instructions
+ *
+ * The platform/OS is running as a guest/virtual machine and uses
+ * IN/OUT instructions in place of string I/O.
+ *
+ * Examples include TDX guest & SEV.
+ */
+ CC_ATTR_GUEST_UNROLL_STRING_IO,
};
#ifdef CONFIG_ARCH_HAS_CC_PLATFORM
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