Messages in this thread Patch in this message |  | | Subject | Re: [RFC v2 28/32] x86/tdx: Make pages shared in ioremap() | | From | "Kuppuswamy, Sathyanarayanan" <> | | Date | Tue, 25 May 2021 11:21:21 -0700 |
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Hi,
On 5/21/21 2:14 PM, Tom Lendacky wrote: > > > On 5/21/21 1:49 PM, Borislav Petkov wrote: >> On Fri, May 21, 2021 at 11:19:15AM -0500, Tom Lendacky wrote: >>> In arch/x86/mm/mem_encrypt.c, sme_early_init() (should have renamed that >>> when SEV support was added), we do: >>> if (sev_active()) >>> swiotlb_force = SWIOTLB_FORCE; >>> >>> TDX should be able to do a similar thing without having to touch >>> arch/x86/kernel/pci-swiotlb.c. >>> >>> That would remove any confusion over SME being part of a >>> protected_guest_has() call. >> >> Even better. >> >>> I kinda like the separate function, though. >> >> Only if you clean it up and get rid of the inverted logic and drop that >> silly switch-case. >> >>> Except mem_encrypt_active() covers both SME and SEV, so >>> protected_guest_has() would be confusing. >> >> I don't understand - the AMD-specific function amd_protected_guest_has() >> would return sme_me_mask just like mem_encrypt_active() does and we can >> get rid of latter. >> >> Or do you have a problem with the name protected_guest_has() containing >> "guest" while we're talking about SME here? > > The latter. > >> >> If so, feel free to suggest a better one - the name does not have to >> have "guest" in it. > > Let me see if I can come up with something that will make sense. > > Thanks, > Tom > >> >> Thx. >> >>
Following is the sample implementation. Please let me know your comments.
tdx: Introduce generic protected_guest abstraction
Add a generic way to check if we run with an encrypted guest, without requiring x86 specific ifdefs. This can then be used in non architecture specific code.
is_protected_guest() helper function can be implemented using arch specific CPU feature flags.
protected_guest_has() is used to check for protected guest feature flags.
Originally-by: Andi Kleen <ak@linux.intel.com> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
diff --git a/arch/Kconfig b/arch/Kconfig index ecfd3520b676..98c30312555b 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -956,6 +956,9 @@ config HAVE_ARCH_NVRAM_OPS config ISA_BUS_API def_bool ISA
+config ARCH_HAS_PROTECTED_GUEST + bool + # # ABI hall of shame # diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index bc91c4aa7ce4..2f31613be965 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -879,6 +879,7 @@ config INTEL_TDX_GUEST select X86_X2APIC select SECURITY_LOCKDOWN_LSM select X86_MEM_ENCRYPT_COMMON + select ARCH_HAS_PROTECTED_GUEST help Provide support for running in a trusted domain on Intel processors equipped with Trusted Domain eXtenstions. TDX is a new Intel diff --git a/arch/x86/include/asm/protected_guest.h b/arch/x86/include/asm/protected_guest.h new file mode 100644 index 000000000000..b2838e58ce94 --- /dev/null +++ b/arch/x86/include/asm/protected_guest.h @@ -0,0 +1,24 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* Copyright (C) 2020 Intel Corporation */ +#ifndef _ASM_PROTECTED_GUEST +#define _ASM_PROTECTED_GUEST 1 + +#include <asm/cpufeature.h> +#include <asm/tdx.h> + +/* Only include through linux/protected_guest.h */ + +static inline bool is_protected_guest(void) +{ + return boot_cpu_has(X86_FEATURE_TDX_GUEST); +} + +static inline bool protected_guest_has(unsigned long flag) +{ + if (boot_cpu_has(X86_FEATURE_TDX_GUEST)) + return tdx_protected_guest_has(flag); + + return false; +} + +#endif diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h index 175cebb7bf94..d894111f49ea 100644 --- a/arch/x86/include/asm/tdx.h +++ b/arch/x86/include/asm/tdx.h @@ -147,6 +147,7 @@ do { \ extern phys_addr_t tdg_shared_mask(void); extern int tdx_hcall_gpa_intent(phys_addr_t gpa, int numpages, enum tdx_map_type map_type); +bool tdx_protected_guest_has(unsigned long flag);
#else // !CONFIG_INTEL_TDX_GUEST
@@ -167,6 +168,11 @@ static inline int tdx_hcall_gpa_intent(phys_addr_t gpa, int numpages, { return -ENODEV; } + +static inline bool tdx_protected_guest_has(unsigned long flag) +{ + return false; +} #endif /* CONFIG_INTEL_TDX_GUEST */
#ifdef CONFIG_INTEL_TDX_GUEST_KVM diff --git a/arch/x86/kernel/tdx.c b/arch/x86/kernel/tdx.c index c613c89d0d6a..cbb893412b43 100644 --- a/arch/x86/kernel/tdx.c +++ b/arch/x86/kernel/tdx.c @@ -11,6 +11,7 @@ #include <linux/sched/signal.h> /* force_sig_fault() */ #include <linux/swiotlb.h> #include <linux/security.h> +#include <linux/protected_guest.h>
#include <linux/cpu.h>
@@ -122,6 +123,23 @@ bool is_tdx_guest(void) } EXPORT_SYMBOL_GPL(is_tdx_guest);
+bool tdx_protected_guest_has(unsigned long flag) +{ + if (!is_tdx_guest()) + return false; + + switch (flag) { + case VM_MEM_ENCRYPT: + case VM_MEM_ENCRYPT_ACTIVE: + case VM_UNROLL_STRING_IO: + case VM_HOST_MEM_ENCRYPT: + return true; + } + + return false; +} +EXPORT_SYMBOL_GPL(tdx_protected_guest_has); + /* The highest bit of a guest physical address is the "sharing" bit */ phys_addr_t tdg_shared_mask(void) { diff --git a/include/linux/protected_guest.h b/include/linux/protected_guest.h new file mode 100644 index 000000000000..f362eea39bd8 --- /dev/null +++ b/include/linux/protected_guest.h @@ -0,0 +1,23 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +#ifndef _LINUX_PROTECTED_GUEST_H +#define _LINUX_PROTECTED_GUEST_H 1 + +/* Protected Guest Feature Flags (leave 0-0xff for arch specific flags) */ + +/* Support for guest encryption */ +#define VM_MEM_ENCRYPT 0x100 +/* Encryption support is active */ +#define VM_MEM_ENCRYPT_ACTIVE 0x101 +/* Support for unrolled string IO */ +#define VM_UNROLL_STRING_IO 0x102 +/* Support for host memory encryption */ +#define VM_HOST_MEM_ENCRYPT 0x103 + +#ifdef CONFIG_ARCH_HAS_PROTECTED_GUEST +#include <asm/protected_guest.h> +#else +static inline bool is_protected_guest(void) { return false; } +static inline bool protected_guest_has(unsigned long flag) { return false; } +#endif + +#endif
-- Sathyanarayanan Kuppuswamy Linux Kernel Developer
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