Re: [RFC v2-fix-v2 1/1] x86: Introduce generic protected guest abstraction
From: Kuppuswamy, Sathyanarayanan
Date: Thu Jun 03 2021 - 14:34:04 EST
On 6/3/21 11:14 AM, Borislav Petkov wrote:
On Tue, Jun 01, 2021 at 02:14:17PM -0700, Kuppuswamy Sathyanarayanan wrote:
diff --git a/include/linux/protected_guest.h b/include/linux/protected_guest.h
new file mode 100644
index 000000000000..303dfba81d52
--- /dev/null
+++ b/include/linux/protected_guest.h
@@ -0,0 +1,40 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef _LINUX_PROTECTED_GUEST_H
+#define _LINUX_PROTECTED_GUEST_H 1
+
+#include <linux/mem_encrypt.h>
+
+/* Protected Guest Feature Flags (leave 0-0xff for arch specific flags) */
+
+/* Support for guest encryption */
+#define VM_MEM_ENCRYPT 0x100
+/* Encryption support is active */
+#define VM_MEM_ENCRYPT_ACTIVE 0x101
+/* Support for unrolled string IO */
+#define VM_UNROLL_STRING_IO 0x102
+/* Support for host memory encryption */
+#define VM_HOST_MEM_ENCRYPT 0x103
+/* Support for shared mapping initialization (after early init) */
+#define VM_SHARED_MAPPING_INIT 0x104
Ok, a couple of things:
first of all, those flags with that VM_ prefix make me think of
"virtual memory" instead of "virtual machine". So they should be
something else, like, say
PR_G_... for Protected Guest or so. Or PR_GUEST or ...
I would prefer PR_GUEST over PR_G_
(yeah, good namespaces are all taken. )
Then, about the function name length, I'm fine if we did:
prot_guest_has()
or something even shorter, if you folks have a good suggestion.
Anyway, below is a diff ontop of your tree with what I think the
barebones of this should be.
As a reply to this message I went and converted sme_active() to use
protected_guest_has() too.
Comments, complaints?
Thx.
---
diff --git a/arch/x86/include/asm/mem_encrypt.h b/arch/x86/include/asm/mem_encrypt.h
index 1492b0eb29d0..9c80c68d75b5 100644
--- a/arch/x86/include/asm/mem_encrypt.h
+++ b/arch/x86/include/asm/mem_encrypt.h
@@ -56,8 +56,6 @@ bool sev_es_active(void);
#define __bss_decrypted __section(".bss..decrypted")
-bool amd_protected_guest_has(unsigned long flag);
-
#else /* !CONFIG_AMD_MEM_ENCRYPT */
#define sme_me_mask 0ULL
@@ -88,8 +86,6 @@ early_set_memory_encrypted(unsigned long vaddr, unsigned long size) { return 0;
static inline void mem_encrypt_free_decrypted_mem(void) { }
-static inline bool amd_protected_guest_has(unsigned long flag) { return false; }
-
#define __bss_decrypted
#endif /* CONFIG_AMD_MEM_ENCRYPT */
diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
index fa5cd05d3b5b..f09996c6a272 100644
--- a/arch/x86/include/asm/sev.h
+++ b/arch/x86/include/asm/sev.h
@@ -11,6 +11,7 @@
#include <linux/types.h>
#include <asm/insn.h>
#include <asm/sev-common.h>
+#include <asm/pgtable_types.h>
#define GHCB_PROTO_OUR 0x0001UL
#define GHCB_PROTOCOL_MAX 1ULL
@@ -81,12 +82,15 @@ static __always_inline void sev_es_nmi_complete(void)
__sev_es_nmi_complete();
}
extern int __init sev_es_efi_map_ghcbs(pgd_t *pgd);
+bool sev_protected_guest_has(unsigned long flag);
+
#else
static inline void sev_es_ist_enter(struct pt_regs *regs) { }
static inline void sev_es_ist_exit(void) { }
static inline int sev_es_setup_ap_jump_table(struct real_mode_header *rmh) { return 0; }
static inline void sev_es_nmi_complete(void) { }
static inline int sev_es_efi_map_ghcbs(pgd_t *pgd) { return 0; }
+static inline bool sev_protected_guest_has(unsigned long flag) { return false; }
#endif
-#endif
+#endif /* __ASM_ENCRYPTED_STATE_H */
diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index f7a743d122eb..01a224fdb897 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -1402,3 +1402,14 @@ bool __init handle_vc_boot_ghcb(struct pt_regs *regs)
while (true)
halt();
}
+
+bool sev_protected_guest_has(unsigned long flag)
+{
+ switch (flag) {
+ case VM_MEM_ENCRYPT:
+ case VM_MEM_ENCRYPT_ACTIVE:
+ return true;
+ }
+
+ return false;
+}
I assume this file will get compiled for both SEV and SME cases.
diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
index ced658e79753..49d11bb6e02a 100644
--- a/arch/x86/mm/mem_encrypt.c
+++ b/arch/x86/mm/mem_encrypt.c
@@ -391,18 +391,6 @@ bool noinstr sev_es_active(void)
return sev_status & MSR_AMD64_SEV_ES_ENABLED;
}
-bool amd_protected_guest_has(unsigned long flag)
-{
- switch (flag) {
- case VM_MEM_ENCRYPT:
- case VM_MEM_ENCRYPT_ACTIVE:
- return true;
- }
-
- return false;
-}
-EXPORT_SYMBOL_GPL(amd_protected_guest_has);
-
/* Override for DMA direct allocation check - AMD specific initialization */
bool amd_force_dma_unencrypted(struct device *dev)
{
diff --git a/include/linux/protected_guest.h b/include/linux/protected_guest.h
index 6855d5b3e244..bb4b1a06b21f 100644
--- a/include/linux/protected_guest.h
+++ b/include/linux/protected_guest.h
@@ -2,7 +2,9 @@
#ifndef _LINUX_PROTECTED_GUEST_H
#define _LINUX_PROTECTED_GUEST_H 1
-#include <linux/mem_encrypt.h>
+#include <asm/processor.h>
+#include <asm/tdx.h>
+#include <asm/sev.h>
/* Protected Guest Feature Flags (leave 0-0xff for arch specific flags) */
@@ -20,23 +22,18 @@
#define VM_DISABLE_UNCORE_SUPPORT 0x105
#if defined(CONFIG_INTEL_TDX_GUEST) || defined(CONFIG_AMD_MEM_ENCRYPT)
-
-#include <asm/tdx.h>
-
static inline bool protected_guest_has(unsigned long flag)
{
if (is_tdx_guest())
return tdx_protected_guest_has(flag);
- else if (mem_encrypt_active())
- return amd_protected_guest_has(flag);
+ else if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
+ return sev_protected_guest_has(flag);
Since you are checking for AMD vendor ID, why not use amd_protected_guest_has()?
return false;
}
#else
-
static inline bool protected_guest_has(unsigned long flag) { return false; }
-
#endif
-#endif
+#endif /* _LINUX_PROTECTED_GUEST_H */
--
Sathyanarayanan Kuppuswamy
Linux Kernel Developer