[RFC 10/12] x86/pconfig: Program memory encryption keys on a system-wide basis
From: Huang, Kai <hidden>
Date: 2018-09-10 01:46:26
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keyrings, linux-mm
quoted hunk ↗ jump to hunk
-----Original Message----- From: Schofield, Alison Sent: Saturday, September 8, 2018 10:38 AM To: dhowells at redhat.com; tglx at linutronix.de Cc: Huang, Kai <redacted>; Nakajima, Jun [off-list ref]; Shutemov, Kirill [off-list ref]; Hansen, Dave [off-list ref]; Sakkinen, Jarkko [off-list ref]; jmorris at namei.org; keyrings at vger.kernel.org; linux-security-module at vger.kernel.org; mingo at redhat.com; hpa at zytor.com; x86 at kernel.org; linux-mm at kvack.org Subject: [RFC 10/12] x86/pconfig: Program memory encryption keys on a system-wide basis The kernel manages the MKTME (Multi-Key Total Memory Encryption) Keys as a system wide single pool of keys. The hardware, however, manages the keys on a per physical package basis. Each physical package maintains a key table that all CPU's in that package share. In order to maintain the consistent, system wide view that the kernel requires, program all physical packages during a key program request. Signed-off-by: Alison Schofield <alison.schofield@intel.com> --- arch/x86/include/asm/intel_pconfig.h | 42 ++++++++++++++++++++++++++++++------ 1 file changed, 36 insertions(+), 6 deletions(-)diff --git a/arch/x86/include/asm/intel_pconfig.hb/arch/x86/include/asm/intel_pconfig.h index 3cb002b1d0f9..d3bf0a297e89 100644--- a/arch/x86/include/asm/intel_pconfig.h +++ b/arch/x86/include/asm/intel_pconfig.h@@ -3,6 +3,7 @@ #include <asm/asm.h> #include <asm/processor.h> +#include <linux/cpu.h> enum pconfig_target { INVALID_TARGET = 0,@@ -47,19 +48,48 @@ struct mktme_key_program { u8 key_field_2[64]; } __packed __aligned(256); -static inline int mktme_key_program(struct mktme_key_program*key_program) +struct mktme_key_program_info { + struct mktme_key_program *key_program; + unsigned long status; +}; + +static void mktme_package_program(void *key_program_info) { + struct mktme_key_program_info *info = key_program_info; unsigned long rax = MKTME_KEY_PROGRAM; + asm volatile(PCONFIG + : "=a" (rax), "=b" (info->key_program)
Why do we need "=b" (info->key_program)? To me PCONFIG only reads from rbx, but won't write to it.
+ : "0" (rax), "1" (info->key_program)
+ : "memory", "cc");
+
+ if (rax != MKTME_PROG_SUCCESS)
+ WRITE_ONCE(info->status, rax);
+}
+
+/*
+ * MKTME keys are managed as a system-wide single pool of keys.
+ * In the hardware, each physical package maintains a separate key
+ * table. Program all physical packages with the same key info to
+ * maintain that system-wide kernel view.
+ */
+static inline int mktme_key_program(struct mktme_key_program
*key_program,
+ cpumask_var_t mktme_cpumask)
+{
+ struct mktme_key_program_info info = {
+ .key_program = key_program,
+ .status = MKTME_PROG_SUCCESS,
+ };
+
if (!pconfig_target_supported(MKTME_TARGET))
return -ENXIO;
- asm volatile(PCONFIG
- : "=a" (rax), "=b" (key_program)
- : "0" (rax), "1" (key_program)
- : "memory", "cc");
+ get_online_cpus();
+ on_each_cpu_mask(mktme_cpumask, mktme_package_program,
+ &info, 1);
+ put_online_cpus();What is the value of 'mktme_cpumask'? Does it only contain one core for each package? Since we are using 'on_each_cpu_mask', I think we should make sure only one core is set for each node in 'mktme_cpumask'. Otherwise we have to deal with 'DEVICE_BUSY' case, since if one core is already in middle of PCONFIG, the other PCONFIGs on the same node would get 'DEVICE_BUSY' error, but this doesn't mean PCONFIG has failed on that node. Thanks, -Kai
- return rax; + return info.status; } #endif /* _ASM_X86_INTEL_PCONFIG_H */ -- 2.14.1