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Message-ID: <7144c0d5-8fb4-8d83-a854-ed597296c68f@amd.com>
Date: Mon, 15 Jan 2024 09:53:24 -0600
From: Tom Lendacky <thomas.lendacky@....com>
To: Kevin Loughlin <kevinloughlin@...gle.com>,
Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>,
x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
Andy Lutomirski <luto@...nel.org>, Peter Zijlstra <peterz@...radead.org>,
Nathan Chancellor <nathan@...nel.org>,
Nick Desaulniers <ndesaulniers@...gle.com>, Bill Wendling
<morbo@...gle.com>, Justin Stitt <justinstitt@...gle.com>,
Michael Kelley <mikelley@...rosoft.com>, Pankaj Gupta
<pankaj.gupta@....com>, Stephen Rothwell <sfr@...b.auug.org.au>,
Arnd Bergmann <arnd@...db.de>, Steve Rutherford <srutherford@...gle.com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Hou Wenlong <houwenlong.hwl@...group.com>,
Vegard Nossum <vegard.nossum@...cle.com>,
Josh Poimboeuf <jpoimboe@...nel.org>, Yuntao Wang <ytcoode@...il.com>,
Wang Jinchao <wangjinchao@...sion.com>, David Woodhouse <dwmw@...zon.co.uk>,
Brian Gerst <brgerst@...il.com>, Hugh Dickins <hughd@...gle.com>,
Ard Biesheuvel <ardb@...nel.org>, Joerg Roedel <jroedel@...e.de>,
Randy Dunlap <rdunlap@...radead.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
Dionna Glaze <dionnaglaze@...gle.com>, Brijesh Singh
<brijesh.singh@....com>, Michael Roth <michael.roth@....com>,
"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
linux-kernel@...r.kernel.org, llvm@...ts.linux.dev,
linux-coco@...ts.linux.dev, Ashish Kalra <ashish.kalra@....com>,
Andi Kleen <ak@...ux.intel.com>
Cc: Adam Dunlap <acdunlap@...gle.com>, Peter Gonda <pgonda@...gle.com>,
Jacob Xu <jacobhxu@...gle.com>, Sidharth Telang <sidtelang@...gle.com>
Subject: Re: [RFC PATCH v2] x86/sev: enforce RIP-relative accesses in early
SEV/SME code
On 1/11/24 16:36, Kevin Loughlin wrote:
> SEV/SME code can execute prior to page table fixups for kernel
> relocation. However, as with global variables accessed in
> __startup_64(), the compiler is not required to generate RIP-relative
> accesses for SEV/SME global variables, causing certain flavors of SEV
> hosts and guests built with clang to crash during boot.
>
> While an attempt was made to force RIP-relative addressing for certain
> global SEV/SME variables via inline assembly (see snp_cpuid_get_table()
> for example), RIP-relative addressing must be pervasively-enforced for
> SEV/SME global variables when accessed prior to page table fixups.
>
> __startup_64() already handles this issue for select non-SEV/SME global
> variables using fixup_pointer(), which adjusts the pointer relative to
> a `physaddr` argument. To avoid having to pass around this `physaddr`
> argument across all functions needing to apply pointer fixups, this
> patch introduces the macro GET_RIP_RELATIVE_PTR() (an abstraction of
> the existing snp_cpuid_get_table()), which generates an RIP-relative
> pointer to a passed variable. Similarly, PTR_TO_RIP_RELATIVE_PTR() is
> introduced to fixup an existing pointer value with RIP-relative logic.
>
> Applying these macros to early SEV/SME code (alongside Adam Dunlap's
> necessary "[PATCH v2] x86/asm: Force native_apic_mem_read to use mov")
> enables previously-failing boots of clang builds to succeed, while
> preserving successful boot of gcc builds. Tested with and without SEV,
> SEV-ES, SEV-SNP enabled in guests built via both gcc and clang.
>
> Fixes: 95d33bfaa3e1 ("x86/sev: Register GHCB memory when SEV-SNP is active")
> Fixes: ee0bfa08a345 ("x86/compressed/64: Add support for SEV-SNP CPUID table in #VC handlers")
> Fixes: 1cd9c22fee3a ("x86/mm/encrypt: Move page table helpers into separate translation unit")
> Fixes: c9f09539e16e ("x86/head/64: Check SEV encryption before switching to kernel page-table")
> Fixes: b577f542f93c ("x86/coco: Add API to handle encryption mask")
> Tested-by: Kevin Loughlin <kevinloughlin@...gle.com>
> Signed-off-by: Kevin Loughlin <kevinloughlin@...gle.com>
> ---
> arch/x86/coco/core.c | 22 +++++++----
> arch/x86/include/asm/mem_encrypt.h | 37 +++++++++++++++++-
> arch/x86/kernel/head64.c | 22 ++++++-----
> arch/x86/kernel/head_64.S | 4 +-
> arch/x86/kernel/sev-shared.c | 63 ++++++++++++++++--------------
> arch/x86/kernel/sev.c | 15 +++++--
> arch/x86/mm/mem_encrypt_identity.c | 50 ++++++++++++------------
> 7 files changed, 136 insertions(+), 77 deletions(-)
>
> diff --git a/arch/x86/coco/core.c b/arch/x86/coco/core.c
> index eeec9986570e..8c45b5643f48 100644
> --- a/arch/x86/coco/core.c
> +++ b/arch/x86/coco/core.c
> @@ -5,6 +5,11 @@
> * Copyright (C) 2021 Advanced Micro Devices, Inc.
> *
> * Author: Tom Lendacky <thomas.lendacky@....com>
> + *
> + * WARNING!!
> + * Select functions in this file can execute prior to page table fixups and thus
> + * require pointer fixups for global variable accesses. See WARNING in
> + * arch/x86/kernel/head64.c.
> */
>
> #include <linux/export.h>
> @@ -61,33 +66,34 @@ static __maybe_unused __always_inline bool amd_cc_platform_vtom(enum cc_attr att
> static bool noinstr amd_cc_platform_has(enum cc_attr attr)
> {
> #ifdef CONFIG_AMD_MEM_ENCRYPT
> + const u64 sev_status_fixed_up = sev_get_status_fixup();
Why not also have a variable for sme_me_mask?
>
> - if (sev_status & MSR_AMD64_SNP_VTOM)
> + if (sev_status_fixed_up & MSR_AMD64_SNP_VTOM)
> return amd_cc_platform_vtom(attr);
>
> switch (attr) {
> case CC_ATTR_MEM_ENCRYPT:
> - return sme_me_mask;
> + return sme_get_me_mask_fixup();
>
> case CC_ATTR_HOST_MEM_ENCRYPT:
> - return sme_me_mask && !(sev_status & MSR_AMD64_SEV_ENABLED);
> + return sme_get_me_mask_fixup() && !(sev_status_fixed_up & MSR_AMD64_SEV_ENABLED);
>
> case CC_ATTR_GUEST_MEM_ENCRYPT:
> - return sev_status & MSR_AMD64_SEV_ENABLED;
> + return sev_status_fixed_up & MSR_AMD64_SEV_ENABLED;
>
> case CC_ATTR_GUEST_STATE_ENCRYPT:
> - return sev_status & MSR_AMD64_SEV_ES_ENABLED;
> + return sev_status_fixed_up & MSR_AMD64_SEV_ES_ENABLED;
>
> /*
> * With SEV, the rep string I/O instructions need to be unrolled
> * but SEV-ES supports them through the #VC handler.
> */
> case CC_ATTR_GUEST_UNROLL_STRING_IO:
> - return (sev_status & MSR_AMD64_SEV_ENABLED) &&
> - !(sev_status & MSR_AMD64_SEV_ES_ENABLED);
> + return (sev_status_fixed_up & MSR_AMD64_SEV_ENABLED) &&
> + !(sev_status_fixed_up & MSR_AMD64_SEV_ES_ENABLED);
>
> case CC_ATTR_GUEST_SEV_SNP:
> - return sev_status & MSR_AMD64_SEV_SNP_ENABLED;
> + return sev_status_fixed_up & MSR_AMD64_SEV_SNP_ENABLED;
>
> default:
> return false;
> diff --git a/arch/x86/include/asm/mem_encrypt.h b/arch/x86/include/asm/mem_encrypt.h
> index 359ada486fa9..d007050a0edc 100644
> --- a/arch/x86/include/asm/mem_encrypt.h
> +++ b/arch/x86/include/asm/mem_encrypt.h
> @@ -17,6 +17,34 @@
>
> #include <asm/bootparam.h>
>
> +/*
> + * Generates an RIP-relative pointer to a data variable "var".
> + * This macro can be used to safely access global data variables prior to kernel
> + * relocation, similar to fixup_pointer() in arch/x86/kernel/head64.c.
> + */
> +#define GET_RIP_RELATIVE_PTR(var) \
> +({ \
> + void *rip_rel_ptr; \
> + asm ("lea "#var"(%%rip), %0" \
> + : "=r" (rip_rel_ptr) \
> + : "p" (&var)); \
> + rip_rel_ptr; \
> +})
> +
> +/*
> + * Converts an existing pointer "ptr" to an RIP-relative pointer.
> + * This macro can be used to safely access global pointers prior to kernel
> + * relocation, similar to fixup_pointer() in arch/x86/kernel/head64.c.
> + */
> +#define PTR_TO_RIP_RELATIVE_PTR(ptr) \
> +({ \
> + void *rip_rel_ptr; \
> + asm ("lea "#ptr"(%%rip), %0" \
> + : "=r" (rip_rel_ptr) \
> + : "p" (ptr)); \
> + rip_rel_ptr; \
> +})
> +
> #ifdef CONFIG_X86_MEM_ENCRYPT
> void __init mem_encrypt_init(void);
> void __init mem_encrypt_setup_arch(void);
> @@ -106,9 +134,14 @@ void add_encrypt_protection_map(void);
>
> extern char __start_bss_decrypted[], __end_bss_decrypted[], __start_bss_decrypted_unused[];
>
> -static inline u64 sme_get_me_mask(void)
> +static inline u64 sme_get_me_mask_fixup(void)
> +{
> + return *((u64 *) GET_RIP_RELATIVE_PTR(sme_me_mask));
> +}
> +
> +static inline u64 sev_get_status_fixup(void)
> {
> - return sme_me_mask;
> + return *((u64 *) GET_RIP_RELATIVE_PTR(sev_status));
> }
>
> #endif /* __ASSEMBLY__ */
> diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
> index dc0956067944..8df7a198094d 100644
> --- a/arch/x86/kernel/head64.c
> +++ b/arch/x86/kernel/head64.c
> @@ -130,6 +130,7 @@ static unsigned long __head sme_postprocess_startup(struct boot_params *bp, pmdv
> {
> unsigned long vaddr, vaddr_end;
> int i;
> + const u64 sme_me_mask_fixed_up = sme_get_me_mask_fixup();
Should be the first variable listed given the length of the line.
>
> /* Encrypt the kernel and related (if SME is active) */
> sme_encrypt_kernel(bp);
> @@ -140,7 +141,7 @@ static unsigned long __head sme_postprocess_startup(struct boot_params *bp, pmdv
> * there is no need to zero it after changing the memory encryption
> * attribute.
> */
> - if (sme_get_me_mask()) {
> + if (sme_me_mask_fixed_up) {
> vaddr = (unsigned long)__start_bss_decrypted;
> vaddr_end = (unsigned long)__end_bss_decrypted;
>
> @@ -158,7 +159,7 @@ static unsigned long __head sme_postprocess_startup(struct boot_params *bp, pmdv
> early_snp_set_memory_shared(__pa(vaddr), __pa(vaddr), PTRS_PER_PMD);
>
> i = pmd_index(vaddr);
> - pmd[i] -= sme_get_me_mask();
> + pmd[i] -= sme_me_mask_fixed_up;
> }
> }
>
> @@ -166,14 +167,16 @@ static unsigned long __head sme_postprocess_startup(struct boot_params *bp, pmdv
> * Return the SME encryption mask (if SME is active) to be used as a
> * modifier for the initial pgdir entry programmed into CR3.
> */
> - return sme_get_me_mask();
> + return sme_me_mask_fixed_up;
> }
>
> -/* Code in __startup_64() can be relocated during execution, but the compiler
> +/*
> + * WARNING!!
> + * Code in __startup_64() can be relocated during execution, but the compiler
> * doesn't have to generate PC-relative relocations when accessing globals from
> * that function. Clang actually does not generate them, which leads to
> * boot-time crashes. To work around this problem, every global pointer must
> - * be adjusted using fixup_pointer().
> + * be adjusted using fixup_pointer() or GET_RIP_RELATIVE_PTR().
> */
> unsigned long __head __startup_64(unsigned long physaddr,
> struct boot_params *bp)
> @@ -188,6 +191,7 @@ unsigned long __head __startup_64(unsigned long physaddr,
> bool la57;
> int i;
> unsigned int *next_pgt_ptr;
> + const u64 sme_me_mask_fixed_up = sme_get_me_mask_fixup();
Ditto, here, this should be higher in the variable list.
>
> la57 = check_la57_support(physaddr);
>
> @@ -206,7 +210,7 @@ unsigned long __head __startup_64(unsigned long physaddr,
> for (;;);
>
> /* Include the SME encryption mask in the fixup value */
> - load_delta += sme_get_me_mask();
> + load_delta += sme_me_mask_fixed_up;
>
> /* Fixup the physical addresses in the page table */
>
> @@ -242,7 +246,7 @@ unsigned long __head __startup_64(unsigned long physaddr,
> pud = fixup_pointer(early_dynamic_pgts[(*next_pgt_ptr)++], physaddr);
> pmd = fixup_pointer(early_dynamic_pgts[(*next_pgt_ptr)++], physaddr);
>
> - pgtable_flags = _KERNPG_TABLE_NOENC + sme_get_me_mask();
> + pgtable_flags = _KERNPG_TABLE_NOENC + sme_me_mask_fixed_up;
>
> if (la57) {
> p4d = fixup_pointer(early_dynamic_pgts[(*next_pgt_ptr)++],
> @@ -269,7 +273,7 @@ unsigned long __head __startup_64(unsigned long physaddr,
> /* Filter out unsupported __PAGE_KERNEL_* bits: */
> mask_ptr = fixup_pointer(&__supported_pte_mask, physaddr);
> pmd_entry &= *mask_ptr;
> - pmd_entry += sme_get_me_mask();
> + pmd_entry += sme_me_mask_fixed_up;
> pmd_entry += physaddr;
>
> for (i = 0; i < DIV_ROUND_UP(_end - _text, PMD_SIZE); i++) {
> @@ -313,7 +317,7 @@ unsigned long __head __startup_64(unsigned long physaddr,
> * Fixup phys_base - remove the memory encryption mask to obtain
> * the true physical address.
> */
> - *fixup_long(&phys_base, physaddr) += load_delta - sme_get_me_mask();
> + *fixup_long(&phys_base, physaddr) += load_delta - sme_me_mask_fixed_up;
>
> return sme_postprocess_startup(bp, pmd);
> }
> diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
> index d4918d03efb4..b9e52cee6e00 100644
> --- a/arch/x86/kernel/head_64.S
> +++ b/arch/x86/kernel/head_64.S
> @@ -176,9 +176,11 @@ SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL)
> /*
> * Retrieve the modifier (SME encryption mask if SME is active) to be
> * added to the initial pgdir entry that will be programmed into CR3.
> + * Since we may have not completed page table fixups, use RIP-relative
> + * addressing for sme_me_mask.
> */
> #ifdef CONFIG_AMD_MEM_ENCRYPT
> - movq sme_me_mask, %rax
> + movq sme_me_mask(%rip), %rax
> #else
> xorq %rax, %rax
> #endif
> diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c
> index 1d24ec679915..e71752c990ef 100644
> --- a/arch/x86/kernel/sev-shared.c
> +++ b/arch/x86/kernel/sev-shared.c
> @@ -7,6 +7,11 @@
> * This file is not compiled stand-alone. It contains code shared
> * between the pre-decompression boot code and the running Linux kernel
> * and is included directly into both code-bases.
> + *
> + * WARNING!!
> + * Select functions in this file can execute prior to page table fixups and thus
> + * require pointer fixups for global variable accesses. See WARNING in
> + * arch/x86/kernel/head64.c.
> */
>
> #ifndef __BOOT_COMPRESSED
> @@ -110,8 +115,9 @@ static void __noreturn sev_es_terminate(unsigned int set, unsigned int reason)
> static u64 get_hv_features(void)
> {
> u64 val;
> + const u16 *ghcb_version_ptr = (const u16 *) GET_RIP_RELATIVE_PTR(ghcb_version);
Is this one really needed? The ghcb_version variable isn't referenced
before fixup, right? It's referenced in both decompression and early boot,
but I didn't think a fixup is needed.
Can you elaborate on the call tree/call time when this is needed?
>
> - if (ghcb_version < 2)
> + if (*ghcb_version_ptr < 2)
> return 0;
>
> sev_es_wr_ghcb_msr(GHCB_MSR_HV_FT_REQ);
> @@ -143,6 +149,7 @@ static void snp_register_ghcb_early(unsigned long paddr)
> static bool sev_es_negotiate_protocol(void)
> {
> u64 val;
> + u16 *ghcb_version_ptr;
>
> /* Do the GHCB protocol version negotiation */
> sev_es_wr_ghcb_msr(GHCB_MSR_SEV_INFO_REQ);
> @@ -156,7 +163,8 @@ static bool sev_es_negotiate_protocol(void)
> GHCB_MSR_PROTO_MIN(val) > GHCB_PROTOCOL_MAX)
> return false;
>
> - ghcb_version = min_t(size_t, GHCB_MSR_PROTO_MAX(val), GHCB_PROTOCOL_MAX);
> + ghcb_version_ptr = (u16 *) GET_RIP_RELATIVE_PTR(ghcb_version);
> + *ghcb_version_ptr = min_t(size_t, GHCB_MSR_PROTO_MAX(val), GHCB_PROTOCOL_MAX);
Ditto here.
>
> return true;
> }
> @@ -318,23 +326,6 @@ static int sev_cpuid_hv(struct ghcb *ghcb, struct es_em_ctxt *ctxt, struct cpuid
> : __sev_cpuid_hv_msr(leaf);
> }
>
> -/*
> - * This may be called early while still running on the initial identity
> - * mapping. Use RIP-relative addressing to obtain the correct address
> - * while running with the initial identity mapping as well as the
> - * switch-over to kernel virtual addresses later.
> - */
> -static const struct snp_cpuid_table *snp_cpuid_get_table(void)
> -{
> - void *ptr;
> -
> - asm ("lea cpuid_table_copy(%%rip), %0"
> - : "=r" (ptr)
> - : "p" (&cpuid_table_copy));
> -
> - return ptr;
> -}
> -
> /*
> * The SNP Firmware ABI, Revision 0.9, Section 7.1, details the use of
> * XCR0_IN and XSS_IN to encode multiple versions of 0xD subfunctions 0
> @@ -357,7 +348,8 @@ static const struct snp_cpuid_table *snp_cpuid_get_table(void)
> */
> static u32 snp_cpuid_calc_xsave_size(u64 xfeatures_en, bool compacted)
> {
> - const struct snp_cpuid_table *cpuid_table = snp_cpuid_get_table();
> + const struct snp_cpuid_table *cpuid_table = (const struct
> + snp_cpuid_table *) GET_RIP_RELATIVE_PTR(cpuid_table_copy);
Can you use typeof in the macro to eliminate this casting? Right now the
macro returns void * so the casting isn't really needed, too, right?
Otherwise, I say move the assignment out of the variable section.
> u64 xfeatures_found = 0;
> u32 xsave_size = 0x240;
> int i;
> @@ -394,7 +386,8 @@ static u32 snp_cpuid_calc_xsave_size(u64 xfeatures_en, bool compacted)
> static bool
> snp_cpuid_get_validated_func(struct cpuid_leaf *leaf)
> {
> - const struct snp_cpuid_table *cpuid_table = snp_cpuid_get_table();
> + const struct snp_cpuid_table *cpuid_table = (const struct
> + snp_cpuid_table *) GET_RIP_RELATIVE_PTR(cpuid_table_copy);
Ditto here.
> int i;
>
> for (i = 0; i < cpuid_table->count; i++) {
> @@ -530,7 +523,9 @@ static int snp_cpuid_postprocess(struct ghcb *ghcb, struct es_em_ctxt *ctxt,
> */
> static int snp_cpuid(struct ghcb *ghcb, struct es_em_ctxt *ctxt, struct cpuid_leaf *leaf)
> {
> - const struct snp_cpuid_table *cpuid_table = snp_cpuid_get_table();
> + const struct snp_cpuid_table *cpuid_table = (const struct
> + snp_cpuid_table *) GET_RIP_RELATIVE_PTR(cpuid_table_copy);
> + const u32 *cpuid_std_range_max_ptr, *cpuid_hyp_range_max_ptr, *cpuid_ext_range_max_ptr;
Move this to the top of the variable definitions.
>
> if (!cpuid_table->count)
> return -EOPNOTSUPP;
> @@ -555,10 +550,14 @@ static int snp_cpuid(struct ghcb *ghcb, struct es_em_ctxt *ctxt, struct cpuid_le
> */
> leaf->eax = leaf->ebx = leaf->ecx = leaf->edx = 0;
>
> + cpuid_std_range_max_ptr = (const u32 *) GET_RIP_RELATIVE_PTR(cpuid_std_range_max);
> + cpuid_hyp_range_max_ptr = (const u32 *) GET_RIP_RELATIVE_PTR(cpuid_hyp_range_max);
> + cpuid_ext_range_max_ptr = (const u32 *) GET_RIP_RELATIVE_PTR(cpuid_ext_range_max);
> +
> /* Skip post-processing for out-of-range zero leafs. */
> - if (!(leaf->fn <= cpuid_std_range_max ||
> - (leaf->fn >= 0x40000000 && leaf->fn <= cpuid_hyp_range_max) ||
> - (leaf->fn >= 0x80000000 && leaf->fn <= cpuid_ext_range_max)))
> + if (!(leaf->fn <= *cpuid_std_range_max_ptr ||
> + (leaf->fn >= 0x40000000 && leaf->fn <= *cpuid_hyp_range_max_ptr) ||
> + (leaf->fn >= 0x80000000 && leaf->fn <= *cpuid_ext_range_max_ptr)))
> return 0;
> }
>
> @@ -1046,6 +1045,7 @@ static struct cc_blob_sev_info *find_cc_blob_setup_data(struct boot_params *bp)
> static void __init setup_cpuid_table(const struct cc_blob_sev_info *cc_info)
> {
> const struct snp_cpuid_table *cpuid_table_fw, *cpuid_table;
> + u32 *cpuid_std_range_max_ptr, *cpuid_hyp_range_max_ptr, *cpuid_ext_range_max_ptr;
Move this to the top of the variable definitions.
> int i;
>
> if (!cc_info || !cc_info->cpuid_phys || cc_info->cpuid_len < PAGE_SIZE)
> @@ -1055,19 +1055,24 @@ static void __init setup_cpuid_table(const struct cc_blob_sev_info *cc_info)
> if (!cpuid_table_fw->count || cpuid_table_fw->count > SNP_CPUID_COUNT_MAX)
> sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_CPUID);
>
> - cpuid_table = snp_cpuid_get_table();
> + cpuid_table = (const struct snp_cpuid_table *) GET_RIP_RELATIVE_PTR(
> + cpuid_table_copy);
This can be a single line since the requirements are now 100 character
line length.
> memcpy((void *)cpuid_table, cpuid_table_fw, sizeof(*cpuid_table));
>
> + cpuid_std_range_max_ptr = (u32 *) GET_RIP_RELATIVE_PTR(cpuid_std_range_max);
> + cpuid_hyp_range_max_ptr = (u32 *) GET_RIP_RELATIVE_PTR(cpuid_hyp_range_max);
> + cpuid_ext_range_max_ptr = (u32 *) GET_RIP_RELATIVE_PTR(cpuid_ext_range_max);
> +
> /* Initialize CPUID ranges for range-checking. */
> for (i = 0; i < cpuid_table->count; i++) {
> const struct snp_cpuid_fn *fn = &cpuid_table->fn[i];
>
> if (fn->eax_in == 0x0)
> - cpuid_std_range_max = fn->eax;
> + *cpuid_std_range_max_ptr = fn->eax;
> else if (fn->eax_in == 0x40000000)
> - cpuid_hyp_range_max = fn->eax;
> + *cpuid_hyp_range_max_ptr = fn->eax;
> else if (fn->eax_in == 0x80000000)
> - cpuid_ext_range_max = fn->eax;
> + *cpuid_ext_range_max_ptr = fn->eax;
> }
> }
>
> diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
> index c67285824e82..c966bc511949 100644
> --- a/arch/x86/kernel/sev.c
> +++ b/arch/x86/kernel/sev.c
> @@ -5,6 +5,11 @@
> * Copyright (C) 2019 SUSE
> *
> * Author: Joerg Roedel <jroedel@...e.de>
> + *
> + * WARNING!!
> + * Select functions in this file can execute prior to page table fixups and thus
> + * require pointer fixups for global variable accesses. See WARNING in
> + * arch/x86/kernel/head64.c.
> */
>
> #define pr_fmt(fmt) "SEV: " fmt
> @@ -748,7 +753,7 @@ void __init early_snp_set_memory_private(unsigned long vaddr, unsigned long padd
> * This eliminates worries about jump tables or checking boot_cpu_data
> * in the cc_platform_has() function.
> */
> - if (!(sev_status & MSR_AMD64_SEV_SNP_ENABLED))
> + if (!(sev_get_status_fixup() & MSR_AMD64_SEV_SNP_ENABLED))
> return;
>
> /*
> @@ -767,7 +772,7 @@ void __init early_snp_set_memory_shared(unsigned long vaddr, unsigned long paddr
> * This eliminates worries about jump tables or checking boot_cpu_data
> * in the cc_platform_has() function.
> */
> - if (!(sev_status & MSR_AMD64_SEV_SNP_ENABLED))
> + if (!(sev_get_status_fixup() & MSR_AMD64_SEV_SNP_ENABLED))
> return;
>
> /* Ask hypervisor to mark the memory pages shared in the RMP table. */
> @@ -2114,7 +2119,8 @@ void __init __noreturn snp_abort(void)
>
> static void dump_cpuid_table(void)
> {
> - const struct snp_cpuid_table *cpuid_table = snp_cpuid_get_table();
> + const struct snp_cpuid_table *cpuid_table = (const struct
> + snp_cpuid_table *) GET_RIP_RELATIVE_PTR(cpuid_table_copy);
Same comment on the casting and placement.
> int i = 0;
>
> pr_info("count=%d reserved=0x%x reserved2=0x%llx\n",
> @@ -2138,7 +2144,8 @@ static void dump_cpuid_table(void)
> */
> static int __init report_cpuid_table(void)
> {
> - const struct snp_cpuid_table *cpuid_table = snp_cpuid_get_table();
> + const struct snp_cpuid_table *cpuid_table = (const struct
> + snp_cpuid_table *) GET_RIP_RELATIVE_PTR(cpuid_table_copy);
Ditto.
>
> if (!cpuid_table->count)
> return 0;
> diff --git a/arch/x86/mm/mem_encrypt_identity.c b/arch/x86/mm/mem_encrypt_identity.c
> index d73aeb16417f..f4c864ea2468 100644
> --- a/arch/x86/mm/mem_encrypt_identity.c
> +++ b/arch/x86/mm/mem_encrypt_identity.c
> @@ -5,6 +5,11 @@
> * Copyright (C) 2016 Advanced Micro Devices, Inc.
> *
> * Author: Tom Lendacky <thomas.lendacky@....com>
> + *
> + * WARNING!!
> + * Select functions in this file can execute prior to page table fixups and thus
> + * require pointer fixups for global variable accesses. See WARNING in
> + * arch/x86/kernel/head64.c.
> */
>
> #define DISABLE_BRANCH_PROFILING
> @@ -305,7 +310,7 @@ void __init sme_encrypt_kernel(struct boot_params *bp)
> * instrumentation or checking boot_cpu_data in the cc_platform_has()
> * function.
> */
> - if (!sme_get_me_mask() || sev_status & MSR_AMD64_SEV_ENABLED)
> + if (!sme_get_me_mask_fixup() || sev_get_status_fixup() & MSR_AMD64_SEV_ENABLED)
> return;
>
> /*
> @@ -346,9 +351,7 @@ void __init sme_encrypt_kernel(struct boot_params *bp)
> * We're running identity mapped, so we must obtain the address to the
> * SME encryption workarea using rip-relative addressing.
> */
> - asm ("lea sme_workarea(%%rip), %0"
> - : "=r" (workarea_start)
> - : "p" (sme_workarea));
> + workarea_start = (unsigned long) PTR_TO_RIP_RELATIVE_PTR(sme_workarea);
>
> /*
> * Calculate required number of workarea bytes needed:
> @@ -511,7 +514,7 @@ void __init sme_enable(struct boot_params *bp)
> unsigned long me_mask;
> char buffer[16];
> bool snp;
> - u64 msr;
> + u64 msr, *sme_me_mask_ptr, *sev_status_ptr;
Move up in the variable definitions to maintain coding standards.
>
> snp = snp_init(bp);
>
> @@ -542,12 +545,14 @@ void __init sme_enable(struct boot_params *bp)
>
> me_mask = 1UL << (ebx & 0x3f);
>
> + sev_status_ptr = (u64 *) GET_RIP_RELATIVE_PTR(sev_status);
> +
> /* Check the SEV MSR whether SEV or SME is enabled */
> - sev_status = __rdmsr(MSR_AMD64_SEV);
> - feature_mask = (sev_status & MSR_AMD64_SEV_ENABLED) ? AMD_SEV_BIT : AMD_SME_BIT;
> + *sev_status_ptr = __rdmsr(MSR_AMD64_SEV);
You can remove the extra spaces before the "=" now since there isn't any
alignment to be done.
Thanks,
Tom
> + feature_mask = (*sev_status_ptr & MSR_AMD64_SEV_ENABLED) ? AMD_SEV_BIT : AMD_SME_BIT;
>
> /* The SEV-SNP CC blob should never be present unless SEV-SNP is enabled. */
> - if (snp && !(sev_status & MSR_AMD64_SEV_SNP_ENABLED))
> + if (snp && !(*sev_status_ptr & MSR_AMD64_SEV_SNP_ENABLED))
> snp_abort();
>
> /* Check if memory encryption is enabled */
> @@ -573,7 +578,8 @@ void __init sme_enable(struct boot_params *bp)
> return;
> } else {
> /* SEV state cannot be controlled by a command line option */
> - sme_me_mask = me_mask;
> + sme_me_mask_ptr = (u64 *) GET_RIP_RELATIVE_PTR(sme_me_mask);
> + *sme_me_mask_ptr = me_mask;
> goto out;
> }
>
> @@ -582,15 +588,9 @@ void __init sme_enable(struct boot_params *bp)
> * identity mapped, so we must obtain the address to the SME command
> * line argument data using rip-relative addressing.
> */
> - asm ("lea sme_cmdline_arg(%%rip), %0"
> - : "=r" (cmdline_arg)
> - : "p" (sme_cmdline_arg));
> - asm ("lea sme_cmdline_on(%%rip), %0"
> - : "=r" (cmdline_on)
> - : "p" (sme_cmdline_on));
> - asm ("lea sme_cmdline_off(%%rip), %0"
> - : "=r" (cmdline_off)
> - : "p" (sme_cmdline_off));
> + cmdline_arg = (const char *) PTR_TO_RIP_RELATIVE_PTR(sme_cmdline_arg);
> + cmdline_on = (const char *) PTR_TO_RIP_RELATIVE_PTR(sme_cmdline_on);
> + cmdline_off = (const char *) PTR_TO_RIP_RELATIVE_PTR(sme_cmdline_off);
>
> if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT))
> active_by_default = true;
> @@ -603,16 +603,18 @@ void __init sme_enable(struct boot_params *bp)
> if (cmdline_find_option(cmdline_ptr, cmdline_arg, buffer, sizeof(buffer)) < 0)
> return;
>
> + sme_me_mask_ptr = (u64 *) GET_RIP_RELATIVE_PTR(sme_me_mask);
> +
> if (!strncmp(buffer, cmdline_on, sizeof(buffer)))
> - sme_me_mask = me_mask;
> + *sme_me_mask_ptr = me_mask;
> else if (!strncmp(buffer, cmdline_off, sizeof(buffer)))
> - sme_me_mask = 0;
> + *sme_me_mask_ptr = 0;
> else
> - sme_me_mask = active_by_default ? me_mask : 0;
> + *sme_me_mask_ptr = active_by_default ? me_mask : 0;
> out:
> - if (sme_me_mask) {
> - physical_mask &= ~sme_me_mask;
> + if (*sme_me_mask_ptr) {
> + physical_mask &= ~(*sme_me_mask_ptr);
> cc_vendor = CC_VENDOR_AMD;
> - cc_set_mask(sme_me_mask);
> + cc_set_mask(*sme_me_mask_ptr);
> }
> }
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