| Message ID | 20161110003838.3280.23327.stgit@tlendack-t1.amdoffice.net (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Nov 09, 2016 at 06:38:38PM -0600, Tom Lendacky wrote: > This patch adds the support to check if SME has been enabled and if the > mem_encrypt=on command line option is set. If both of these conditions > are true, then the encryption mask is set and the kernel is encrypted > "in place." Something went wrong here - 19/20 and 20/20 have the same Subject and commit message. Care to resend only 19 and 20 with the above fixed? Thanks.
On Wed, Nov 09, 2016 at 06:38:38PM -0600, Tom Lendacky wrote: > This patch adds the support to check if SME has been enabled and if the > mem_encrypt=on command line option is set. If both of these conditions > are true, then the encryption mask is set and the kernel is encrypted > "in place." > > Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> > --- > arch/x86/kernel/head_64.S | 1 + > arch/x86/kernel/mem_encrypt_init.c | 60 +++++++++++++++++++++++++++++++++++- > arch/x86/mm/mem_encrypt.c | 2 + > 3 files changed, 62 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S > index e8a7272..c225433 100644 > --- a/arch/x86/kernel/head_64.S > +++ b/arch/x86/kernel/head_64.S > @@ -100,6 +100,7 @@ startup_64: > * to include it in the page table fixups. > */ > push %rsi > + movq %rsi, %rdi > call sme_enable > pop %rsi > movq %rax, %r12 > diff --git a/arch/x86/kernel/mem_encrypt_init.c b/arch/x86/kernel/mem_encrypt_init.c > index 7bdd159..c94ceb8 100644 > --- a/arch/x86/kernel/mem_encrypt_init.c > +++ b/arch/x86/kernel/mem_encrypt_init.c > @@ -16,9 +16,14 @@ > #include <linux/mm.h> > > #include <asm/sections.h> > +#include <asm/processor-flags.h> > +#include <asm/msr.h> > +#include <asm/cmdline.h> > > #ifdef CONFIG_AMD_MEM_ENCRYPT > > +static char sme_cmdline_arg[] __initdata = "mem_encrypt=on"; One more thing: just like we're adding an =on switch, we'd need an =off switch in case something's wrong with the SME code. IOW, if a user supplies "mem_encrypt=off", we do not encrypt. Thanks.
On 11/26/2016 2:47 PM, Borislav Petkov wrote: > On Wed, Nov 09, 2016 at 06:38:38PM -0600, Tom Lendacky wrote: >> This patch adds the support to check if SME has been enabled and if the >> mem_encrypt=on command line option is set. If both of these conditions >> are true, then the encryption mask is set and the kernel is encrypted >> "in place." >> >> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> >> --- >> arch/x86/kernel/head_64.S | 1 + >> arch/x86/kernel/mem_encrypt_init.c | 60 +++++++++++++++++++++++++++++++++++- >> arch/x86/mm/mem_encrypt.c | 2 + >> 3 files changed, 62 insertions(+), 1 deletion(-) >> >> diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S >> index e8a7272..c225433 100644 >> --- a/arch/x86/kernel/head_64.S >> +++ b/arch/x86/kernel/head_64.S >> @@ -100,6 +100,7 @@ startup_64: >> * to include it in the page table fixups. >> */ >> push %rsi >> + movq %rsi, %rdi >> call sme_enable >> pop %rsi >> movq %rax, %r12 >> diff --git a/arch/x86/kernel/mem_encrypt_init.c b/arch/x86/kernel/mem_encrypt_init.c >> index 7bdd159..c94ceb8 100644 >> --- a/arch/x86/kernel/mem_encrypt_init.c >> +++ b/arch/x86/kernel/mem_encrypt_init.c >> @@ -16,9 +16,14 @@ >> #include <linux/mm.h> >> >> #include <asm/sections.h> >> +#include <asm/processor-flags.h> >> +#include <asm/msr.h> >> +#include <asm/cmdline.h> >> >> #ifdef CONFIG_AMD_MEM_ENCRYPT >> >> +static char sme_cmdline_arg[] __initdata = "mem_encrypt=on"; > > One more thing: just like we're adding an =on switch, we'd need an =off > switch in case something's wrong with the SME code. IOW, if a user > supplies "mem_encrypt=off", we do not encrypt. Well, we can document "off", but if the exact string "mem_encrypt=on" isn't specified on the command line then the encryption won't occur. The cmdline_find_option_bool() function looks for the exact string and isn't interpreting the value on the right side of the equal sign. So omitting mem_encrypt=on or using mem_encrypt=off is the same. Thanks, Tom > > Thanks. > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Nov 29, 2016 at 12:48:17PM -0600, Tom Lendacky wrote: > > One more thing: just like we're adding an =on switch, we'd need an =off > > switch in case something's wrong with the SME code. IOW, if a user > > supplies "mem_encrypt=off", we do not encrypt. > > Well, we can document "off", but if the exact string "mem_encrypt=on" > isn't specified on the command line then the encryption won't occur. So you have this: + /* + * Fixups have not been to applied phys_base yet, so we must obtain + * the address to the SME command line option in the following way. + */ + asm ("lea sme_cmdline_arg(%%rip), %0" + : "=r" (cmdline_arg) + : "p" (sme_cmdline_arg)); + cmdline_ptr = bp->hdr.cmd_line_ptr | ((u64)bp->ext_cmd_line_ptr << 32); + if (cmdline_find_option_bool((char *)cmdline_ptr, cmdline_arg)) + sme_me_mask = 1UL << (ebx & 0x3f); If I parse this right, we will enable SME *only* if mem_encrypt=on is explicitly supplied on the command line. Which means, users will have to *know* about that cmdline switch first. Which then means, we have to go and tell them. Do you see where I'm going with this? I know we talked about this already but I still think we should enable it by default and people who don't want it will use the =off switch. We can also do something like CONFIG_AMD_SME_ENABLED_BY_DEFAULT which we can be selected during build for the different setups. Hmmm.
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index e8a7272..c225433 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -100,6 +100,7 @@ startup_64: * to include it in the page table fixups. */ push %rsi + movq %rsi, %rdi call sme_enable pop %rsi movq %rax, %r12 diff --git a/arch/x86/kernel/mem_encrypt_init.c b/arch/x86/kernel/mem_encrypt_init.c index 7bdd159..c94ceb8 100644 --- a/arch/x86/kernel/mem_encrypt_init.c +++ b/arch/x86/kernel/mem_encrypt_init.c @@ -16,9 +16,14 @@ #include <linux/mm.h> #include <asm/sections.h> +#include <asm/processor-flags.h> +#include <asm/msr.h> +#include <asm/cmdline.h> #ifdef CONFIG_AMD_MEM_ENCRYPT +static char sme_cmdline_arg[] __initdata = "mem_encrypt=on"; + extern void sme_encrypt_execute(unsigned long, unsigned long, unsigned long, void *, pgd_t *); @@ -219,7 +224,60 @@ unsigned long __init sme_get_me_mask(void) return sme_me_mask; } -unsigned long __init sme_enable(void) +unsigned long __init sme_enable(void *boot_data) { +#ifdef CONFIG_AMD_MEM_ENCRYPT + struct boot_params *bp = boot_data; + unsigned int eax, ebx, ecx, edx; + u64 msr; + unsigned long cmdline_ptr; + void *cmdline_arg; + + /* Check for an AMD processor */ + eax = 0; + ecx = 0; + native_cpuid(&eax, &ebx, &ecx, &edx); + if ((ebx != 0x68747541) || (edx != 0x69746e65) || (ecx != 0x444d4163)) + goto out; + + /* Check for the SME support leaf */ + eax = 0x80000000; + ecx = 0; + native_cpuid(&eax, &ebx, &ecx, &edx); + if (eax < 0x8000001f) + goto out; + + /* + * Check for the SME feature: + * CPUID Fn8000_001F[EAX] - Bit 0 + * Secure Memory Encryption support + * CPUID Fn8000_001F[EBX] - Bits 5:0 + * Pagetable bit position used to indicate encryption + */ + eax = 0x8000001f; + ecx = 0; + native_cpuid(&eax, &ebx, &ecx, &edx); + if (!(eax & 1)) + goto out; + + /* Check if SME is enabled */ + msr = native_read_msr(MSR_K8_SYSCFG); + if (!(msr & MSR_K8_SYSCFG_MEM_ENCRYPT)) + goto out; + + /* + * Fixups have not been to applied phys_base yet, so we must obtain + * the address to the SME command line option in the following way. + */ + asm ("lea sme_cmdline_arg(%%rip), %0" + : "=r" (cmdline_arg) + : "p" (sme_cmdline_arg)); + cmdline_ptr = bp->hdr.cmd_line_ptr | ((u64)bp->ext_cmd_line_ptr << 32); + if (cmdline_find_option_bool((char *)cmdline_ptr, cmdline_arg)) + sme_me_mask = 1UL << (ebx & 0x3f); + +out: +#endif /* CONFIG_AMD_MEM_ENCRYPT */ + return sme_me_mask; } diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c index e351003..d0bc3f5 100644 --- a/arch/x86/mm/mem_encrypt.c +++ b/arch/x86/mm/mem_encrypt.c @@ -251,6 +251,8 @@ void __init mem_encrypt_init(void) /* Make SWIOTLB use an unencrypted DMA area */ swiotlb_clear_encryption(); + + pr_info("AMD Secure Memory Encryption active\n"); } void swiotlb_set_mem_unenc(void *vaddr, unsigned long size)
This patch adds the support to check if SME has been enabled and if the mem_encrypt=on command line option is set. If both of these conditions are true, then the encryption mask is set and the kernel is encrypted "in place." Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> --- arch/x86/kernel/head_64.S | 1 + arch/x86/kernel/mem_encrypt_init.c | 60 +++++++++++++++++++++++++++++++++++- arch/x86/mm/mem_encrypt.c | 2 + 3 files changed, 62 insertions(+), 1 deletion(-) -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html