diff options
120 files changed, 3134 insertions, 470 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 3a99cc96b6b1..dad6fa01af95 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2233,6 +2233,17 @@ memory contents and reserves bad memory regions that are detected. + mem_encrypt= [X86-64] AMD Secure Memory Encryption (SME) control + Valid arguments: on, off + Default (depends on kernel configuration option): + on (CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT=y) + off (CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT=n) + mem_encrypt=on: Activate SME + mem_encrypt=off: Do not activate SME + + Refer to Documentation/x86/amd-memory-encryption.txt + for details on when memory encryption can be activated. + mem_sleep_default= [SUSPEND] Default system suspend mode: s2idle - Suspend-To-Idle shallow - Power-On Suspend or equivalent (if supported) @@ -2697,6 +2708,8 @@ nopat [X86] Disable PAT (page attribute table extension of pagetables) support. + nopcid [X86-64] Disable the PCID cpu feature. + norandmaps Don't use address space randomization. Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space diff --git a/Documentation/x86/amd-memory-encryption.txt b/Documentation/x86/amd-memory-encryption.txt new file mode 100644 index 000000000000..f512ab718541 --- /dev/null +++ b/Documentation/x86/amd-memory-encryption.txt @@ -0,0 +1,68 @@ +Secure Memory Encryption (SME) is a feature found on AMD processors. + +SME provides the ability to mark individual pages of memory as encrypted using +the standard x86 page tables. A page that is marked encrypted will be +automatically decrypted when read from DRAM and encrypted when written to +DRAM. SME can therefore be used to protect the contents of DRAM from physical +attacks on the system. + +A page is encrypted when a page table entry has the encryption bit set (see +below on how to determine its position). The encryption bit can also be +specified in the cr3 register, allowing the PGD table to be encrypted. Each +successive level of page tables can also be encrypted by setting the encryption +bit in the page table entry that points to the next table. This allows the full +page table hierarchy to be encrypted. Note, this means that just because the +encryption bit is set in cr3, doesn't imply the full hierarchy is encyrpted. +Each page table entry in the hierarchy needs to have the encryption bit set to +achieve that. So, theoretically, you could have the encryption bit set in cr3 +so that the PGD is encrypted, but not set the encryption bit in the PGD entry +for a PUD which results in the PUD pointed to by that entry to not be +encrypted. + +Support for SME can be determined through the CPUID instruction. The CPUID +function 0x8000001f reports information related to SME: + + 0x8000001f[eax]: + Bit[0] indicates support for SME + 0x8000001f[ebx]: + Bits[5:0] pagetable bit number used to activate memory + encryption + Bits[11:6] reduction in physical address space, in bits, when + memory encryption is enabled (this only affects + system physical addresses, not guest physical + addresses) + +If support for SME is present, MSR 0xc00100010 (MSR_K8_SYSCFG) can be used to +determine if SME is enabled and/or to enable memory encryption: + + 0xc0010010: + Bit[23] 0 = memory encryption features are disabled + 1 = memory encryption features are enabled + +Linux relies on BIOS to set this bit if BIOS has determined that the reduction +in the physical address space as a result of enabling memory encryption (see +CPUID information above) will not conflict with the address space resource +requirements for the system. If this bit is not set upon Linux startup then +Linux itself will not set it and memory encryption will not be possible. + +The state of SME in the Linux kernel can be documented as follows: + - Supported: + The CPU supports SME (determined through CPUID instruction). + + - Enabled: + Supported and bit 23 of MSR_K8_SYSCFG is set. + + - Active: + Supported, Enabled and the Linux kernel is actively applying + the encryption bit to page table entries (the SME mask in the + kernel is non-zero). + +SME can also be enabled and activated in the BIOS. If SME is enabled and +activated in the BIOS, then all memory accesses will be encrypted and it will +not be necessary to activate the Linux memory encryption support. If the BIOS +merely enables SME (sets bit 23 of the MSR_K8_SYSCFG), then Linux can activate +memory encryption by default (CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT=y) or +by supplying mem_encrypt=on on the kernel command line. However, if BIOS does +not enable SME, then Linux will not be able to activate memory encryption, even +if configured to do so by default or the mem_encrypt=on command line parameter +is specified. diff --git a/Documentation/x86/protection-keys.txt b/Documentation/x86/protection-keys.txt index b64304540821..fa46dcb347bc 100644 --- a/Documentation/x86/protection-keys.txt +++ b/Documentation/x86/protection-keys.txt @@ -34,7 +34,7 @@ with a key. In this example WRPKRU is wrapped by a C function called pkey_set(). int real_prot = PROT_READ|PROT_WRITE; - pkey = pkey_alloc(0, PKEY_DENY_WRITE); + pkey = pkey_alloc(0, PKEY_DISABLE_WRITE); ptr = mmap(NULL, PAGE_SIZE, PROT_NONE, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0); ret = pkey_mprotect(ptr, PAGE_SIZE, real_prot, pkey); ... application runs here @@ -42,9 +42,9 @@ called pkey_set(). Now, if the application needs to update the data at 'ptr', it can gain access, do the update, then remove its write access: - pkey_set(pkey, 0); // clear PKEY_DENY_WRITE + pkey_set(pkey, 0); // clear PKEY_DISABLE_WRITE *ptr = foo; // assign something - pkey_set(pkey, PKEY_DENY_WRIT |