From: Borislav Petkov <bp@alien8.de>
To: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Tom Lendacky <thomas.lendacky@amd.com>,
linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org,
linux-kernel@vger.kernel.org, x86@kernel.org,
iommu@lists.linux-foundation.org, kvm@vger.kernel.org,
linux-efi@vger.kernel.org, platform-driver-x86@vger.kernel.org,
linux-graphics-maintainer@vmware.com,
amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
kexec@lists.infradead.org, linux-fsdevel@vger.kernel.org,
Brijesh Singh <brijesh.singh@amd.com>,
Joerg Roedel <joro@8bytes.org>, Andi Kleen <ak@linux.intel.com>,
Sathyanarayanan Kuppuswamy
<sathyanarayanan.kuppuswamy@linux.intel.com>,
Tianyu Lan <Tianyu.Lan@microsoft.com>,
Christoph Hellwig <hch@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Will Deacon <will@kernel.org>
Subject: Re: [PATCH v3 5/8] x86/sme: Replace occurrences of sme_active() with cc_platform_has()
Date: Thu, 23 Sep 2021 20:21:03 +0200 [thread overview]
Message-ID: <YUzFj+yH79XRc3F3@zn.tnic> (raw)
In-Reply-To: <20210922210558.itofvu3725dap5xx@box.shutemov.name>
On Thu, Sep 23, 2021 at 12:05:58AM +0300, Kirill A. Shutemov wrote:
> Unless we find other way to guarantee RIP-relative access, we must use
> fixup_pointer() to access any global variables.
Yah, I've asked compiler folks about any guarantees we have wrt
rip-relative addresses but it doesn't look good. Worst case, we'd have
to do the fixup_pointer() thing.
In the meantime, Tom and I did some more poking at this and here's a
diff ontop.
The direction being that we'll stick both the AMD and Intel
*cc_platform_has() call into cc_platform.c for which instrumentation
will be disabled so no issues with that.
And that will keep all that querying all together in a single file.
---
diff --git a/arch/x86/include/asm/mem_encrypt.h b/arch/x86/include/asm/mem_encrypt.h
index a73712b6ee0e..2d4f5c17d79c 100644
--- a/arch/x86/include/asm/mem_encrypt.h
+++ b/arch/x86/include/asm/mem_encrypt.h
@@ -51,7 +51,6 @@ void __init mem_encrypt_free_decrypted_mem(void);
void __init mem_encrypt_init(void);
void __init sev_es_init_vc_handling(void);
-bool amd_cc_platform_has(enum cc_attr attr);
#define __bss_decrypted __section(".bss..decrypted")
@@ -74,7 +73,6 @@ static inline void __init sme_encrypt_kernel(struct boot_params *bp) { }
static inline void __init sme_enable(struct boot_params *bp) { }
static inline void sev_es_init_vc_handling(void) { }
-static inline bool amd_cc_platform_has(enum cc_attr attr) { return false; }
static inline int __init
early_set_memory_decrypted(unsigned long vaddr, unsigned long size) { return 0; }
@@ -103,12 +101,6 @@ static inline u64 sme_get_me_mask(void)
return sme_me_mask;
}
-#if defined(CONFIG_CPU_SUP_INTEL) && defined(CONFIG_ARCH_HAS_CC_PLATFORM)
-bool intel_cc_platform_has(enum cc_attr attr);
-#else
-static inline bool intel_cc_platform_has(enum cc_attr attr) { return false; }
-#endif
-
#endif /* __ASSEMBLY__ */
#endif /* __X86_MEM_ENCRYPT_H__ */
diff --git a/arch/x86/kernel/cc_platform.c b/arch/x86/kernel/cc_platform.c
index da54a1805211..97ede7052f77 100644
--- a/arch/x86/kernel/cc_platform.c
+++ b/arch/x86/kernel/cc_platform.c
@@ -13,6 +13,52 @@
#include <asm/processor.h>
+static bool intel_cc_platform_has(enum cc_attr attr)
+{
+#ifdef CONFIG_INTEL_TDX_GUEST
+ return false;
+#else
+ return false;
+#endif
+}
+
+/*
+ * SME and SEV are very similar but they are not the same, so there are
+ * times that the kernel will need to distinguish between SME and SEV. The
+ * cc_platform_has() function is used for this. When a distinction isn't
+ * needed, the CC_ATTR_MEM_ENCRYPT attribute can be used.
+ *
+ * The trampoline code is a good example for this requirement. Before
+ * paging is activated, SME will access all memory as decrypted, but SEV
+ * will access all memory as encrypted. So, when APs are being brought
+ * up under SME the trampoline area cannot be encrypted, whereas under SEV
+ * the trampoline area must be encrypted.
+ */
+static bool amd_cc_platform_has(enum cc_attr attr)
+{
+#ifdef CONFIG_AMD_MEM_ENCRYPT
+ switch (attr) {
+ case CC_ATTR_MEM_ENCRYPT:
+ return sme_me_mask;
+
+ case CC_ATTR_HOST_MEM_ENCRYPT:
+ return sme_me_mask && !(sev_status & MSR_AMD64_SEV_ENABLED);
+
+ case CC_ATTR_GUEST_MEM_ENCRYPT:
+ return sev_status & MSR_AMD64_SEV_ENABLED;
+
+ case CC_ATTR_GUEST_STATE_ENCRYPT:
+ return sev_status & MSR_AMD64_SEV_ES_ENABLED;
+
+ default:
+ return false;
+ }
+#else
+ return false;
+#endif
+}
+
+
bool cc_platform_has(enum cc_attr attr)
{
if (sme_me_mask)
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 53756ff12295..8321c43554a1 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -60,13 +60,6 @@ static u64 msr_test_ctrl_cache __ro_after_init;
*/
static bool cpu_model_supports_sld __ro_after_init;
-#ifdef CONFIG_ARCH_HAS_CC_PLATFORM
-bool intel_cc_platform_has(enum cc_attr attr)
-{
- return false;
-}
-#endif
-
/*
* Processors which have self-snooping capability can handle conflicting
* memory type across CPUs by snooping its own cache. However, there exists
diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
index 9417d404ea92..23d54b810f08 100644
--- a/arch/x86/mm/mem_encrypt.c
+++ b/arch/x86/mm/mem_encrypt.c
@@ -361,38 +361,6 @@ int __init early_set_memory_encrypted(unsigned long vaddr, unsigned long size)
return early_set_memory_enc_dec(vaddr, size, true);
}
-/*
- * SME and SEV are very similar but they are not the same, so there are
- * times that the kernel will need to distinguish between SME and SEV. The
- * cc_platform_has() function is used for this. When a distinction isn't
- * needed, the CC_ATTR_MEM_ENCRYPT attribute can be used.
- *
- * The trampoline code is a good example for this requirement. Before
- * paging is activated, SME will access all memory as decrypted, but SEV
- * will access all memory as encrypted. So, when APs are being brought
- * up under SME the trampoline area cannot be encrypted, whereas under SEV
- * the trampoline area must be encrypted.
- */
-bool amd_cc_platform_has(enum cc_attr attr)
-{
- switch (attr) {
- case CC_ATTR_MEM_ENCRYPT:
- return sme_me_mask;
-
- case CC_ATTR_HOST_MEM_ENCRYPT:
- return sme_me_mask && !(sev_status & MSR_AMD64_SEV_ENABLED);
-
- case CC_ATTR_GUEST_MEM_ENCRYPT:
- return sev_status & MSR_AMD64_SEV_ENABLED;
-
- case CC_ATTR_GUEST_STATE_ENCRYPT:
- return sev_status & MSR_AMD64_SEV_ES_ENABLED;
-
- default:
- return false;
- }
-}
-
/* Override for DMA direct allocation check - ARCH_HAS_FORCE_DMA_UNENCRYPTED */
bool force_dma_unencrypted(struct device *dev)
{
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2021-09-23 18:21 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-08 22:58 [PATCH v3 0/8] Implement generic cc_platform_has() helper function Tom Lendacky
2021-09-08 22:58 ` [PATCH v3 1/8] x86/ioremap: Selectively build arch override encryption functions Tom Lendacky
2021-09-08 22:58 ` [PATCH v3 2/8] mm: Introduce a function to check for confidential computing features Tom Lendacky
2021-09-09 7:35 ` Christophe Leroy
2021-09-10 15:02 ` Borislav Petkov
2021-09-08 22:58 ` [PATCH v3 3/8] x86/sev: Add an x86 version of cc_platform_has() Tom Lendacky
2021-09-11 10:10 ` Borislav Petkov
2021-09-08 22:58 ` [PATCH v3 4/8] powerpc/pseries/svm: Add a powerpc " Tom Lendacky
2021-09-09 7:40 ` Christophe Leroy
2021-09-14 11:58 ` Borislav Petkov
2021-09-14 14:47 ` Christophe Leroy
2021-09-14 14:56 ` Borislav Petkov
2021-09-15 0:28 ` Michael Ellerman
2021-09-15 10:08 ` Borislav Petkov
2021-09-15 17:18 ` Christophe Leroy
2021-09-15 18:47 ` Borislav Petkov
2021-09-16 7:35 ` Christoph Hellwig
2021-09-16 11:51 ` Michael Ellerman
2021-09-08 22:58 ` [PATCH v3 5/8] x86/sme: Replace occurrences of sme_active() with cc_platform_has() Tom Lendacky
2021-09-14 18:24 ` Borislav Petkov
2021-09-20 19:23 ` Kirill A. Shutemov
2021-09-21 17:04 ` Tom Lendacky
2021-09-21 17:47 ` Borislav Petkov
2021-09-21 21:20 ` Kirill A. Shutemov
2021-09-21 21:27 ` Borislav Petkov
2021-09-21 21:34 ` Kirill A. Shutemov
2021-09-21 21:43 ` Tom Lendacky
2021-09-21 21:58 ` Kirill A. Shutemov
2021-09-22 13:40 ` Tom Lendacky
2021-09-22 14:30 ` Kirill A. Shutemov
2021-09-22 19:52 ` Borislav Petkov
2021-09-22 21:05 ` Kirill A. Shutemov
2021-09-23 18:21 ` Borislav Petkov [this message]
2021-09-24 9:41 ` Kirill A. Shutemov
2021-09-24 9:51 ` Borislav Petkov
2021-09-24 13:31 ` Tom Lendacky
2021-09-08 22:58 ` [PATCH v3 6/8] x86/sev: Replace occurrences of sev_active() " Tom Lendacky
2021-09-08 22:58 ` [PATCH v3 7/8] x86/sev: Replace occurrences of sev_es_active() " Tom Lendacky
2021-09-08 22:58 ` [PATCH v3 8/8] treewide: Replace the use of mem_encrypt_active() " Tom Lendacky
2021-09-09 7:25 ` Christophe Leroy
2021-09-09 13:10 ` Tom Lendacky
2021-09-09 7:32 ` [PATCH v3 0/8] Implement generic cc_platform_has() helper function Christian Borntraeger
2021-09-09 13:01 ` Tom Lendacky
2021-09-15 16:46 ` Borislav Petkov
2021-09-15 17:26 ` Kuppuswamy, Sathyanarayanan
2021-09-16 15:02 ` Borislav Petkov
2021-09-16 18:38 ` Kuppuswamy, Sathyanarayanan
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