[PATCHv3.1 2.1/2] x86/coco: Add API to handle encryption mask
From: Kirill A. Shutemov
Date: Fri Feb 18 2022 - 19:12:18 EST
AMD SME/SEV uses a bit in the page table entries to indicate that the
page is encrypted and not accessible to the VMM.
TDX uses a similar approach, but the polarity of the mask is opposite to
AMD: if the bit is set the page is accessible to VMM.
Provide vendor-neutral API to deal with the mask:
- cc_mkenc() and cc_mkdec() modify given address to make it
encrypted/decrypted. It can be applied to phys_addr_t, pgprotval_t
or page table entry value.
- cc_get_mask() returns encryption or decrypthion mask. It is useful
for set_memory_encrypted() and set_memory_decrypted()
implementation.
The implementation will be extended to cover TDX.
pgprot_decrypted() is used by drivers (i915, virtio_gpu, vfio).
cc_mkdec() called by pgprot_decrypted(). Export cc_mkdec().
HyperV doesn't use bits in page table entries, so the mask is 0 for both
encrypthion and decrypthion.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
arch/x86/include/asm/coco.h | 12 +++++++++-
arch/x86/include/asm/pgtable.h | 13 ++++++-----
arch/x86/kernel/cc_platform.c | 35 +++++++++++++++++++++++++++++-
arch/x86/kernel/cpu/mshyperv.c | 2 +-
arch/x86/mm/mem_encrypt_identity.c | 2 +-
arch/x86/mm/pat/set_memory.c | 4 ++--
6 files changed, 56 insertions(+), 12 deletions(-)
diff --git a/arch/x86/include/asm/coco.h b/arch/x86/include/asm/coco.h
index 6e770e0dd683..802d87d08e31 100644
--- a/arch/x86/include/asm/coco.h
+++ b/arch/x86/include/asm/coco.h
@@ -11,6 +11,16 @@ enum cc_vendor {
CC_VENDOR_INTEL,
};
-void cc_init(enum cc_vendor);
+void cc_init(enum cc_vendor, u64 mask);
+
+#ifdef CONFIG_ARCH_HAS_CC_PLATFORM
+u64 cc_get_mask(bool enc);
+u64 cc_mkenc(u64 val);
+u64 cc_mkdec(u64 val);
+#else
+#define cc_get_mask(enc) 0
+#define cc_mkenc(val) (val)
+#define cc_mkdec(val) (val)
+#endif
#endif /* _ASM_X86_COCO_H */
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 8a9432fb3802..62ab07e24aef 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -15,17 +15,12 @@
cachemode2protval(_PAGE_CACHE_MODE_UC_MINUS))) \
: (prot))
-/*
- * Macros to add or remove encryption attribute
- */
-#define pgprot_encrypted(prot) __pgprot(__sme_set(pgprot_val(prot)))
-#define pgprot_decrypted(prot) __pgprot(__sme_clr(pgprot_val(prot)))
-
#ifndef __ASSEMBLY__
#include <linux/spinlock.h>
#include <asm/x86_init.h>
#include <asm/pkru.h>
#include <asm/fpu/api.h>
+#include <asm/coco.h>
#include <asm-generic/pgtable_uffd.h>
#include <linux/page_table_check.h>
@@ -38,6 +33,12 @@ void ptdump_walk_pgd_level_debugfs(struct seq_file *m, struct mm_struct *mm,
void ptdump_walk_pgd_level_checkwx(void);
void ptdump_walk_user_pgd_level_checkwx(void);
+/*
+ * Macros to add or remove encryption attribute
+ */
+#define pgprot_encrypted(prot) __pgprot(cc_mkenc(pgprot_val(prot)))
+#define pgprot_decrypted(prot) __pgprot(cc_mkdec(pgprot_val(prot)))
+
#ifdef CONFIG_DEBUG_WX
#define debug_checkwx() ptdump_walk_pgd_level_checkwx()
#define debug_checkwx_user() ptdump_walk_user_pgd_level_checkwx()
diff --git a/arch/x86/kernel/cc_platform.c b/arch/x86/kernel/cc_platform.c
index 891d3074a16e..93e6be7b7eca 100644
--- a/arch/x86/kernel/cc_platform.c
+++ b/arch/x86/kernel/cc_platform.c
@@ -13,6 +13,7 @@
#include <asm/coco.h>
#include <asm/processor.h>
+static u64 cc_mask;
static enum cc_vendor cc_vendor;
static bool intel_cc_platform_has(enum cc_attr attr)
@@ -84,7 +85,39 @@ bool cc_platform_has(enum cc_attr attr)
}
EXPORT_SYMBOL_GPL(cc_platform_has);
-__init void cc_init(enum cc_vendor vendor)
+u64 cc_get_mask(bool enc)
+{
+ switch (cc_vendor) {
+ case CC_VENDOR_AMD:
+ return enc ? cc_mask : 0;
+ default:
+ return 0;
+ }
+}
+
+u64 cc_mkenc(u64 val)
+{
+ switch (cc_vendor) {
+ case CC_VENDOR_AMD:
+ return val | cc_mask;
+ default:
+ return val;
+ }
+}
+
+u64 cc_mkdec(u64 val)
+{
+ switch (cc_vendor) {
+ case CC_VENDOR_AMD:
+ return val & ~cc_mask;
+ default:
+ return val;
+ }
+}
+EXPORT_SYMBOL_GPL(cc_mkdec);
+
+__init void cc_init(enum cc_vendor vendor, u64 mask)
{
cc_vendor = vendor;
+ cc_mask = mask;
}
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index d77cf3a31f07..9af6be143998 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -346,7 +346,7 @@ static void __init ms_hyperv_init_platform(void)
swiotlb_force = SWIOTLB_FORCE;
#endif
if (hv_get_isolation_type() != HV_ISOLATION_TYPE_NONE)
- cc_init(CC_VENDOR_HYPERV);
+ cc_init(CC_VENDOR_HYPERV, 0);
}
if (hv_max_functions_eax >= HYPERV_CPUID_NESTED_FEATURES) {
diff --git a/arch/x86/mm/mem_encrypt_identity.c b/arch/x86/mm/mem_encrypt_identity.c
index eb7fbd85b77e..fa758247ab57 100644
--- a/arch/x86/mm/mem_encrypt_identity.c
+++ b/arch/x86/mm/mem_encrypt_identity.c
@@ -603,5 +603,5 @@ void __init sme_enable(struct boot_params *bp)
out:
physical_mask &= ~sme_me_mask;
if (sme_me_mask)
- cc_init(CC_VENDOR_AMD);
+ cc_init(CC_VENDOR_AMD, sme_me_mask);
}
diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c
index b4072115c8ef..e79366b8a9da 100644
--- a/arch/x86/mm/pat/set_memory.c
+++ b/arch/x86/mm/pat/set_memory.c
@@ -1999,8 +1999,8 @@ static int __set_memory_enc_pgtable(unsigned long addr, int numpages, bool enc)
memset(&cpa, 0, sizeof(cpa));
cpa.vaddr = &addr;
cpa.numpages = numpages;
- cpa.mask_set = enc ? __pgprot(_PAGE_ENC) : __pgprot(0);
- cpa.mask_clr = enc ? __pgprot(0) : __pgprot(_PAGE_ENC);
+ cpa.mask_set = __pgprot(cc_get_mask(enc));
+ cpa.mask_clr = __pgprot(cc_get_mask(!enc));
cpa.pgd = init_mm.pgd;
/* Must avoid aliasing mappings in the highmem code */
--
2.34.1