From 9999e48639b3cecb08ffb37358bcba3b48161b29 Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Fri, 10 May 2024 08:50:17 +0000
Subject: [PATCH] add ax88772_rst
---
kernel/arch/x86/mm/mem_encrypt_identity.c | 66 ++++++++++++++++++++++----------
1 files changed, 45 insertions(+), 21 deletions(-)
diff --git a/kernel/arch/x86/mm/mem_encrypt_identity.c b/kernel/arch/x86/mm/mem_encrypt_identity.c
index 650d5a6..5ec47af 100644
--- a/kernel/arch/x86/mm/mem_encrypt_identity.c
+++ b/kernel/arch/x86/mm/mem_encrypt_identity.c
@@ -1,13 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0-only
/*
* AMD Memory Encryption Support
*
* Copyright (C) 2016 Advanced Micro Devices, Inc.
*
* Author: Tom Lendacky <thomas.lendacky@amd.com>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
*/
#define DISABLE_BRANCH_PROFILING
@@ -27,6 +24,7 @@
* be extended when new paravirt and debugging variants are added.)
*/
#undef CONFIG_PARAVIRT
+#undef CONFIG_PARAVIRT_XXL
#undef CONFIG_PARAVIRT_SPINLOCKS
/*
@@ -80,6 +78,19 @@
unsigned long vaddr;
unsigned long vaddr_end;
};
+
+/*
+ * This work area lives in the .init.scratch section, which lives outside of
+ * the kernel proper. It is sized to hold the intermediate copy buffer and
+ * more than enough pagetable pages.
+ *
+ * By using this section, the kernel can be encrypted in place and it
+ * avoids any possibility of boot parameters or initramfs images being
+ * placed such that the in-place encryption logic overwrites them. This
+ * section is 2MB aligned to allow for simple pagetable setup using only
+ * PMD entries (see vmlinux.lds.S).
+ */
+static char sme_workarea[2 * PMD_PAGE_SIZE] __section(".init.scratch");
static char sme_cmdline_arg[] __initdata = "mem_encrypt";
static char sme_cmdline_on[] __initdata = "on";
@@ -322,8 +333,13 @@
}
#endif
- /* Set the encryption workarea to be immediately after the kernel */
- workarea_start = kernel_end;
+ /*
+ * We're running identity mapped, so we must obtain the address to the
+ * SME encryption workarea using rip-relative addressing.
+ */
+ asm ("lea sme_workarea(%%rip), %0"
+ : "=r" (workarea_start)
+ : "p" (sme_workarea));
/*
* Calculate required number of workarea bytes needed:
@@ -496,14 +512,6 @@
#define AMD_SME_BIT BIT(0)
#define AMD_SEV_BIT BIT(1)
- /*
- * Set the feature mask (SME or SEV) based on whether we are
- * running under a hypervisor.
- */
- eax = 1;
- ecx = 0;
- native_cpuid(&eax, &ebx, &ecx, &edx);
- feature_mask = (ecx & BIT(31)) ? AMD_SEV_BIT : AMD_SME_BIT;
/*
* Check for the SME/SEV feature:
@@ -516,23 +524,38 @@
eax = 0x8000001f;
ecx = 0;
native_cpuid(&eax, &ebx, &ecx, &edx);
- if (!(eax & feature_mask))
+ /* Check whether SEV or SME is supported */
+ if (!(eax & (AMD_SEV_BIT | AMD_SME_BIT)))
return;
me_mask = 1UL << (ebx & 0x3f);
+ /* Check the SEV MSR whether SEV or SME is enabled */
+ sev_status = __rdmsr(MSR_AMD64_SEV);
+ feature_mask = (sev_status & MSR_AMD64_SEV_ENABLED) ? AMD_SEV_BIT : AMD_SME_BIT;
+
/* Check if memory encryption is enabled */
if (feature_mask == AMD_SME_BIT) {
+ /*
+ * No SME if Hypervisor bit is set. This check is here to
+ * prevent a guest from trying to enable SME. For running as a
+ * KVM guest the MSR_K8_SYSCFG will be sufficient, but there
+ * might be other hypervisors which emulate that MSR as non-zero
+ * or even pass it through to the guest.
+ * A malicious hypervisor can still trick a guest into this
+ * path, but there is no way to protect against that.
+ */
+ eax = 1;
+ ecx = 0;
+ native_cpuid(&eax, &ebx, &ecx, &edx);
+ if (ecx & BIT(31))
+ return;
+
/* For SME, check the SYSCFG MSR */
msr = __rdmsr(MSR_K8_SYSCFG);
if (!(msr & MSR_K8_SYSCFG_MEM_ENCRYPT))
return;
} else {
- /* For SEV, check the SEV MSR */
- msr = __rdmsr(MSR_AMD64_SEV);
- if (!(msr & MSR_AMD64_SEV_ENABLED))
- return;
-
/* SEV state cannot be controlled by a command line option */
sme_me_mask = me_mask;
sev_enabled = true;
@@ -563,7 +586,8 @@
cmdline_ptr = (const char *)((u64)bp->hdr.cmd_line_ptr |
((u64)bp->ext_cmd_line_ptr << 32));
- cmdline_find_option(cmdline_ptr, cmdline_arg, buffer, sizeof(buffer));
+ if (cmdline_find_option(cmdline_ptr, cmdline_arg, buffer, sizeof(buffer)) < 0)
+ return;
if (!strncmp(buffer, cmdline_on, sizeof(buffer)))
sme_me_mask = me_mask;
--
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