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    Subject[PATCH v7 8/9] x86/sev: Move early startup code into .head.text section
    From
    From: Ard Biesheuvel <ardb@kernel.org>

    In preparation for implementing rigorous build time checks to enforce
    that only code that can support it will be called from the early 1:1
    mapping of memory, move SEV init code that is called in this manner to
    the .head.text section.

    Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
    ---
    arch/x86/boot/compressed/sev.c | 3 +++
    arch/x86/include/asm/sev.h | 10 ++++-----
    arch/x86/kernel/sev-shared.c | 23 +++++++++-----------
    arch/x86/kernel/sev.c | 14 +++++++-----
    4 files changed, 26 insertions(+), 24 deletions(-)

    diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c
    index 073291832f44..bea0719d70f2 100644
    --- a/arch/x86/boot/compressed/sev.c
    +++ b/arch/x86/boot/compressed/sev.c
    @@ -116,6 +116,9 @@ static bool fault_in_kernel_space(unsigned long address)
    #undef __init
    #define __init

    +#undef __head
    +#define __head
    +
    #define __BOOT_COMPRESSED

    /* Basic instruction decoding support needed */
    diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
    index bed95e1f4d52..cf671138feef 100644
    --- a/arch/x86/include/asm/sev.h
    +++ b/arch/x86/include/asm/sev.h
    @@ -213,16 +213,16 @@ static inline int pvalidate(unsigned long vaddr, bool rmp_psize, bool validate)
    struct snp_guest_request_ioctl;

    void setup_ghcb(void);
    -void __init early_snp_set_memory_private(unsigned long vaddr, unsigned long paddr,
    - unsigned long npages);
    -void __init early_snp_set_memory_shared(unsigned long vaddr, unsigned long paddr,
    - unsigned long npages);
    +void early_snp_set_memory_private(unsigned long vaddr, unsigned long paddr,
    + unsigned long npages);
    +void early_snp_set_memory_shared(unsigned long vaddr, unsigned long paddr,
    + unsigned long npages);
    void __init snp_prep_memory(unsigned long paddr, unsigned int sz, enum psc_op op);
    void snp_set_memory_shared(unsigned long vaddr, unsigned long npages);
    void snp_set_memory_private(unsigned long vaddr, unsigned long npages);
    void snp_set_wakeup_secondary_cpu(void);
    bool snp_init(struct boot_params *bp);
    -void __init __noreturn snp_abort(void);
    +void __noreturn snp_abort(void);
    int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct snp_guest_request_ioctl *rio);
    void snp_accept_memory(phys_addr_t start, phys_addr_t end);
    u64 snp_get_unsupported_features(u64 status);
    diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c
    index ae79f9505298..0bd7ccbe8732 100644
    --- a/arch/x86/kernel/sev-shared.c
    +++ b/arch/x86/kernel/sev-shared.c
    @@ -93,7 +93,8 @@ static bool __init sev_es_check_cpu_features(void)
    return true;
    }

    -static void __noreturn sev_es_terminate(unsigned int set, unsigned int reason)
    +static void __head __noreturn
    +sev_es_terminate(unsigned int set, unsigned int reason)
    {
    u64 val = GHCB_MSR_TERM_REQ;

    @@ -330,13 +331,7 @@ static int sev_cpuid_hv(struct ghcb *ghcb, struct es_em_ctxt *ctxt, struct cpuid
    */
    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;
    + return &RIP_REL_REF(cpuid_table_copy);
    }

    /*
    @@ -395,7 +390,7 @@ static u32 snp_cpuid_calc_xsave_size(u64 xfeatures_en, bool compacted)
    return xsave_size;
    }

    -static bool
    +static bool __head
    snp_cpuid_get_validated_func(struct cpuid_leaf *leaf)
    {
    const struct snp_cpuid_table *cpuid_table = snp_cpuid_get_table();
    @@ -532,7 +527,8 @@ static int snp_cpuid_postprocess(struct ghcb *ghcb, struct es_em_ctxt *ctxt,
    * Returns -EOPNOTSUPP if feature not enabled. Any other non-zero return value
    * should be treated as fatal by caller.
    */
    -static int snp_cpuid(struct ghcb *ghcb, struct es_em_ctxt *ctxt, struct cpuid_leaf *leaf)
    +static int __head
    +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();

    @@ -574,7 +570,7 @@ static int snp_cpuid(struct ghcb *ghcb, struct es_em_ctxt *ctxt, struct cpuid_le
    * page yet, so it only supports the MSR based communication with the
    * hypervisor and only the CPUID exit-code.
    */
    -void __init do_vc_no_ghcb(struct pt_regs *regs, unsigned long exit_code)
    +void __head do_vc_no_ghcb(struct pt_regs *regs, unsigned long exit_code)
    {
    unsigned int subfn = lower_bits(regs->cx, 32);
    unsigned int fn = lower_bits(regs->ax, 32);
    @@ -1025,7 +1021,8 @@ struct cc_setup_data {
    * Search for a Confidential Computing blob passed in as a setup_data entry
    * via the Linux Boot Protocol.
    */
    -static struct cc_blob_sev_info *find_cc_blob_setup_data(struct boot_params *bp)
    +static __head
    +struct cc_blob_sev_info *find_cc_blob_setup_data(struct boot_params *bp)
    {
    struct cc_setup_data *sd = NULL;
    struct setup_data *hdr;
    @@ -1052,7 +1049,7 @@ static struct cc_blob_sev_info *find_cc_blob_setup_data(struct boot_params *bp)
    * mapping needs to be updated in sync with all the changes to virtual memory
    * layout and related mapping facilities throughout the boot process.
    */
    -static void __init setup_cpuid_table(const struct cc_blob_sev_info *cc_info)
    +static void __head setup_cpuid_table(const struct cc_blob_sev_info *cc_info)
    {
    const struct snp_cpuid_table *cpuid_table_fw, *cpuid_table;
    int i;
    diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
    index 1ef7ae806a01..33c14aa1f06c 100644
    --- a/arch/x86/kernel/sev.c
    +++ b/arch/x86/kernel/sev.c
    @@ -25,6 +25,7 @@
    #include <linux/psp-sev.h>
    #include <uapi/linux/sev-guest.h>

    +#include <asm/init.h>
    #include <asm/cpu_entry_area.h>
    #include <asm/stacktrace.h>
    #include <asm/sev.h>
    @@ -682,8 +683,9 @@ static u64 __init get_jump_table_addr(void)
    return ret;
    }

    -static void early_set_pages_state(unsigned long vaddr, unsigned long paddr,
    - unsigned long npages, enum psc_op op)
    +static void __head
    +early_set_pages_state(unsigned long vaddr, unsigned long paddr,
    + unsigned long npages, enum psc_op op)
    {
    unsigned long paddr_end;
    u64 val;
    @@ -739,7 +741,7 @@ static void early_set_pages_state(unsigned long vaddr, unsigned long paddr,
    sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_PSC);
    }

    -void __init early_snp_set_memory_private(unsigned long vaddr, unsigned long paddr,
    +void __head early_snp_set_memory_private(unsigned long vaddr, unsigned long paddr,
    unsigned long npages)
    {
    /*
    @@ -2062,7 +2064,7 @@ bool __init handle_vc_boot_ghcb(struct pt_regs *regs)
    *
    * Scan for the blob in that order.
    */
    -static __init struct cc_blob_sev_info *find_cc_blob(struct boot_params *bp)
    +static __head struct cc_blob_sev_info *find_cc_blob(struct boot_params *bp)
    {
    struct cc_blob_sev_info *cc_info;

    @@ -2088,7 +2090,7 @@ static __init struct cc_blob_sev_info *find_cc_blob(struct boot_params *bp)
    return cc_info;
    }

    -bool __init snp_init(struct boot_params *bp)
    +bool __head snp_init(struct boot_params *bp)
    {
    struct cc_blob_sev_info *cc_info;

    @@ -2110,7 +2112,7 @@ bool __init snp_init(struct boot_params *bp)
    return true;
    }

    -void __init __noreturn snp_abort(void)
    +void __head __noreturn snp_abort(void)
    {
    sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SNP_UNSUPPORTED);
    }
    --
    2.44.0.rc1.240.g4c46232300-goog

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