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| author | Kirill A. Shutemov <kirill.shutemov@linux.intel.com> | 2022-04-06 01:29:14 +0200 |
|---|---|---|
| committer | Dave Hansen <dave.hansen@linux.intel.com> | 2022-04-07 17:27:51 +0200 |
| commit | 65fab5bc033aad1a9faf976caec46558c2f88319 (patch) | |
| tree | 0e5733b953e294830bc957be45a4c08614502d9e | |
| parent | x86/tdx: Extend the confidential computing API to support TDX guests (diff) | |
| download | linux-65fab5bc033aad1a9faf976caec46558c2f88319.tar.xz linux-65fab5bc033aad1a9faf976caec46558c2f88319.zip | |
x86/tdx: Exclude shared bit from __PHYSICAL_MASK
In TDX guests, by default memory is protected from host access. If a
guest needs to communicate with the VMM (like the I/O use case), it uses
a single bit in the physical address to communicate the protected/shared
attribute of the given page.
In the x86 ARCH code, __PHYSICAL_MASK macro represents the width of the
physical address in the given architecture. It is used in creating
physical PAGE_MASK for address bits in the kernel. Since in TDX guest,
a single bit is used as metadata, it needs to be excluded from valid
physical address bits to avoid using incorrect addresses bits in the
kernel.
Enable DYNAMIC_PHYSICAL_MASK to support updating the __PHYSICAL_MASK.
Co-developed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20220405232939.73860-6-kirill.shutemov@linux.intel.com
| -rw-r--r-- | arch/x86/Kconfig | 1 | ||||
| -rw-r--r-- | arch/x86/coco/tdx/tdx.c | 8 |
2 files changed, 9 insertions, 0 deletions
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 984315ca0275..aea4cc404c31 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -883,6 +883,7 @@ config INTEL_TDX_GUEST depends on X86_64 && CPU_SUP_INTEL depends on X86_X2APIC select ARCH_HAS_CC_PLATFORM + select DYNAMIC_PHYSICAL_MASK help Support running as a guest under Intel TDX. Without this support, the guest kernel can not boot or run under TDX. diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c index 96b2611baac5..e84f6dd3ed2a 100644 --- a/arch/x86/coco/tdx/tdx.c +++ b/arch/x86/coco/tdx/tdx.c @@ -89,5 +89,13 @@ void __init tdx_early_init(void) cc_mask = get_cc_mask(); cc_set_mask(cc_mask); + /* + * All bits above GPA width are reserved and kernel treats shared bit + * as flag, not as part of physical address. + * + * Adjust physical mask to only cover valid GPA bits. + */ + physical_mask &= cc_mask - 1; + pr_info("Guest detected\n"); } |