Messages in this thread | | | Subject | Re: [PATCH v1 2/2] acpi, x86: Remove encryption mask from ACPI page protection type | From | Tom Lendacky <> | Date | Thu, 27 Jul 2017 09:57:45 -0500 |
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On 7/27/2017 9:41 AM, Borislav Petkov wrote: > On Wed, Jul 26, 2017 at 01:04:34PM -0500, Tom Lendacky wrote: >> The function arch_apei_get_mem_attributes() is used to set the page >> protection type for ACPI physical addresses. When SME is active, the >> associated protection type needs to not have the encryption mask set >> since the ACPI tables live in un-encrypted memory. Modify the >> arch_apei_get_mem_attributes() function to remove the encryption mask >> when SME is active by returning the PAGE_KERNEL_IO protection type. >> >> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> >> --- >> arch/x86/include/asm/acpi.h | 7 ++++++- >> 1 file changed, 6 insertions(+), 1 deletion(-) >> >> diff --git a/arch/x86/include/asm/acpi.h b/arch/x86/include/asm/acpi.h >> index 562286f..89df39d 100644 >> --- a/arch/x86/include/asm/acpi.h >> +++ b/arch/x86/include/asm/acpi.h >> @@ -34,6 +34,7 @@ >> >> #ifdef CONFIG_ACPI_APEI >> # include <asm/pgtable_types.h> >> +# include <linux/mem_encrypt.h> >> #endif >> >> #ifdef CONFIG_ACPI >> @@ -164,8 +165,12 @@ static inline pgprot_t arch_apei_get_mem_attribute(phys_addr_t addr) >> * anything other than PAGE_KERNEL (some arm64 platforms >> * require the equivalent of PAGE_KERNEL_NOCACHE), return that >> * until we know differently. >> + * >> + * When SME is active, the ACPI information will not reside in >> + * in memory in an encrypted state so return a protection attribute >> + * that does not have the encryption bit set. >> */ >> - return PAGE_KERNEL; >> + return sme_active() ? PAGE_KERNEL_IO : PAGE_KERNEL; > > Why isn't there a PAGE_KERNEL_NOENC define which you can simply return > instead of testing?
Sounds like something I should add to pgtable_types.h (which has a #define for PAGE_KERNEL_EXEC_NOENC, but not PAGE_KERNEL_NOENC). I'll create that #define.
As for the sme_active() check I was getting ahead of myself since under SEV the encryption mask is needed. I'll change it to just return PAGE_KERNEL_NOENC and then worry about the SEV change in the SEV patches.
Thanks, Tom
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