x86: Restrict KVM-induced symbol exports to KVM modules where obvious/possible

Extend KVM's export macro framework to provide EXPORT_SYMBOL_FOR_KVM(),
and use the helper macro to export symbols for KVM throughout x86 if and
only if KVM will build one or more modules, and only for those modules.

To avoid unnecessary exports when CONFIG_KVM=m but kvm.ko will not be
built (because no vendor modules are selected), let arch code #define
EXPORT_SYMBOL_FOR_KVM to suppress/override the exports.

Note, the set of symbols to restrict to KVM was generated by manual search
and audit; any "misses" are due to human error, not some grand plan.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Kai Huang <kai.huang@intel.com>
Tested-by: Kai Huang <kai.huang@intel.com>
Link: https://patch.msgid.link/20251112173944.1380633-5-seanjc%40google.com

1 files changed, 35 insertions, 34 deletions

diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index eac403248462..5ce4ebe99774 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -29,6 +29,7 @@
 #include <linux/acpi.h>
 #include <linux/suspend.h>
 #include <linux/idr.h>
+#include <linux/kvm_types.h>
 #include <asm/page.h>
 #include <asm/special_insns.h>
 #include <asm/msr-index.h>
@@ -181,7 +182,7 @@ int tdx_cpu_enable(void)
 
 	return 0;
 }
-EXPORT_SYMBOL_GPL(tdx_cpu_enable);
+EXPORT_SYMBOL_FOR_KVM(tdx_cpu_enable);
 
 /*
  * Add a memory region as a TDX memory block.  The caller must make sure
@@ -662,7 +663,7 @@ void tdx_quirk_reset_page(struct page *page)
 {
 	tdx_quirk_reset_paddr(page_to_phys(page), PAGE_SIZE);
 }
-EXPORT_SYMBOL_GPL(tdx_quirk_reset_page);
+EXPORT_SYMBOL_FOR_KVM(tdx_quirk_reset_page);
 
 static void tdmr_quirk_reset_pamt(struct tdmr_info *tdmr)
 {
@@ -1216,7 +1217,7 @@ int tdx_enable(void)
 
 	return ret;
 }
-EXPORT_SYMBOL_GPL(tdx_enable);
+EXPORT_SYMBOL_FOR_KVM(tdx_enable);
 
 static bool is_pamt_page(unsigned long phys)
 {
@@ -1477,13 +1478,13 @@ const struct tdx_sys_info *tdx_get_sysinfo(void)
 
 	return p;
 }
-EXPORT_SYMBOL_GPL(tdx_get_sysinfo);
+EXPORT_SYMBOL_FOR_KVM(tdx_get_sysinfo);
 
 u32 tdx_get_nr_guest_keyids(void)
 {
 	return tdx_nr_guest_keyids;
 }
-EXPORT_SYMBOL_GPL(tdx_get_nr_guest_keyids);
+EXPORT_SYMBOL_FOR_KVM(tdx_get_nr_guest_keyids);
 
 int tdx_guest_keyid_alloc(void)
 {
@@ -1491,13 +1492,13 @@ int tdx_guest_keyid_alloc(void)
 			       tdx_guest_keyid_start + tdx_nr_guest_keyids - 1,
 			       GFP_KERNEL);
 }
-EXPORT_SYMBOL_GPL(tdx_guest_keyid_alloc);
+EXPORT_SYMBOL_FOR_KVM(tdx_guest_keyid_alloc);
 
 void tdx_guest_keyid_free(unsigned int keyid)
 {
 	ida_free(&tdx_guest_keyid_pool, keyid);
 }
-EXPORT_SYMBOL_GPL(tdx_guest_keyid_free);
+EXPORT_SYMBOL_FOR_KVM(tdx_guest_keyid_free);
 
 static inline u64 tdx_tdr_pa(struct tdx_td *td)
 {
@@ -1521,7 +1522,7 @@ noinstr u64 tdh_vp_enter(struct tdx_vp *td, struct tdx_module_args *args)
 
 	return __seamcall_dirty_cache(__seamcall_saved_ret, TDH_VP_ENTER, args);
 }
-EXPORT_SYMBOL_GPL(tdh_vp_enter);
+EXPORT_SYMBOL_FOR_KVM(tdh_vp_enter);
 
 u64 tdh_mng_addcx(struct tdx_td *td, struct page *tdcs_page)
 {
@@ -1533,7 +1534,7 @@ u64 tdh_mng_addcx(struct tdx_td *td, struct page *tdcs_page)
 	tdx_clflush_page(tdcs_page);
 	return seamcall(TDH_MNG_ADDCX, &args);
 }
-EXPORT_SYMBOL_GPL(tdh_mng_addcx);
+EXPORT_SYMBOL_FOR_KVM(tdh_mng_addcx);
 
 u64 tdh_mem_page_add(struct tdx_td *td, u64 gpa, struct page *page, struct page *source, u64 *ext_err1, u64 *ext_err2)
 {
@@ -1553,7 +1554,7 @@ u64 tdh_mem_page_add(struct tdx_td *td, u64 gpa, struct page *page, struct page
 
 	return ret;
 }
-EXPORT_SYMBOL_GPL(tdh_mem_page_add);
+EXPORT_SYMBOL_FOR_KVM(tdh_mem_page_add);
 
 u64 tdh_mem_sept_add(struct tdx_td *td, u64 gpa, int level, struct page *page, u64 *ext_err1, u64 *ext_err2)
 {
@@ -1572,7 +1573,7 @@ u64 tdh_mem_sept_add(struct tdx_td *td, u64 gpa, int level, struct page *page, u
 
 	return ret;
 }
-EXPORT_SYMBOL_GPL(tdh_mem_sept_add);
+EXPORT_SYMBOL_FOR_KVM(tdh_mem_sept_add);
 
 u64 tdh_vp_addcx(struct tdx_vp *vp, struct page *tdcx_page)
 {
@@ -1584,7 +1585,7 @@ u64 tdh_vp_addcx(struct tdx_vp *vp, struct page *tdcx_page)
 	tdx_clflush_page(tdcx_page);
 	return seamcall(TDH_VP_ADDCX, &args);
 }
-EXPORT_SYMBOL_GPL(tdh_vp_addcx);
+EXPORT_SYMBOL_FOR_KVM(tdh_vp_addcx);
 
 u64 tdh_mem_page_aug(struct tdx_td *td, u64 gpa, int level, struct page *page, u64 *ext_err1, u64 *ext_err2)
 {
@@ -1603,7 +1604,7 @@ u64 tdh_mem_page_aug(struct tdx_td *td, u64 gpa, int level, struct page *page, u
 
 	return ret;
 }
-EXPORT_SYMBOL_GPL(tdh_mem_page_aug);
+EXPORT_SYMBOL_FOR_KVM(tdh_mem_page_aug);
 
 u64 tdh_mem_range_block(struct tdx_td *td, u64 gpa, int level, u64 *ext_err1, u64 *ext_err2)
 {
@@ -1620,7 +1621,7 @@ u64 tdh_mem_range_block(struct tdx_td *td, u64 gpa, int level, u64 *ext_err1, u6
 
 	return ret;
 }
-EXPORT_SYMBOL_GPL(tdh_mem_range_block);
+EXPORT_SYMBOL_FOR_KVM(tdh_mem_range_block);
 
 u64 tdh_mng_key_config(struct tdx_td *td)
 {
@@ -1630,7 +1631,7 @@ u64 tdh_mng_key_config(struct tdx_td *td)
 
 	return seamcall(TDH_MNG_KEY_CONFIG, &args);
 }
-EXPORT_SYMBOL_GPL(tdh_mng_key_config);
+EXPORT_SYMBOL_FOR_KVM(tdh_mng_key_config);
 
 u64 tdh_mng_create(struct tdx_td *td, u16 hkid)
 {
@@ -1642,7 +1643,7 @@ u64 tdh_mng_create(struct tdx_td *td, u16 hkid)
 	tdx_clflush_page(td->tdr_page);
 	return seamcall(TDH_MNG_CREATE, &args);
 }
-EXPORT_SYMBOL_GPL(tdh_mng_create);
+EXPORT_SYMBOL_FOR_KVM(tdh_mng_create);
 
 u64 tdh_vp_create(struct tdx_td *td, struct tdx_vp *vp)
 {
@@ -1654,7 +1655,7 @@ u64 tdh_vp_create(struct tdx_td *td, struct tdx_vp *vp)
 	tdx_clflush_page(vp->tdvpr_page);
 	return seamcall(TDH_VP_CREATE, &args);
 }
-EXPORT_SYMBOL_GPL(tdh_vp_create);
+EXPORT_SYMBOL_FOR_KVM(tdh_vp_create);
 
 u64 tdh_mng_rd(struct tdx_td *td, u64 field, u64 *data)
 {
@@ -1671,7 +1672,7 @@ u64 tdh_mng_rd(struct tdx_td *td, u64 field, u64 *data)
 
 	return ret;
 }
-EXPORT_SYMBOL_GPL(tdh_mng_rd);
+EXPORT_SYMBOL_FOR_KVM(tdh_mng_rd);
 
 u64 tdh_mr_extend(struct tdx_td *td, u64 gpa, u64 *ext_err1, u64 *ext_err2)
 {
@@ -1688,7 +1689,7 @@ u64 tdh_mr_extend(struct tdx_td *td, u64 gpa, u64 *ext_err1, u64 *ext_err2)
 
 	return ret;
 }
-EXPORT_SYMBOL_GPL(tdh_mr_extend);
+EXPORT_SYMBOL_FOR_KVM(tdh_mr_extend);
 
 u64 tdh_mr_finalize(struct tdx_td *td)
 {
@@ -1698,7 +1699,7 @@ u64 tdh_mr_finalize(struct tdx_td *td)
 
 	return seamcall(TDH_MR_FINALIZE, &args);
 }
-EXPORT_SYMBOL_GPL(tdh_mr_finalize);
+EXPORT_SYMBOL_FOR_KVM(tdh_mr_finalize);
 
 u64 tdh_vp_flush(struct tdx_vp *vp)
 {
@@ -1708,7 +1709,7 @@ u64 tdh_vp_flush(struct tdx_vp *vp)
 
 	return seamcall(TDH_VP_FLUSH, &args);
 }
-EXPORT_SYMBOL_GPL(tdh_vp_flush);
+EXPORT_SYMBOL_FOR_KVM(tdh_vp_flush);
 
 u64 tdh_mng_vpflushdone(struct tdx_td *td)
 {
@@ -1718,7 +1719,7 @@ u64 tdh_mng_vpflushdone(struct tdx_td *td)
 
 	return seamcall(TDH_MNG_VPFLUSHDONE, &args);
 }
-EXPORT_SYMBOL_GPL(tdh_mng_vpflushdone);
+EXPORT_SYMBOL_FOR_KVM(tdh_mng_vpflushdone);
 
 u64 tdh_mng_key_freeid(struct tdx_td *td)
 {
@@ -1728,7 +1729,7 @@ u64 tdh_mng_key_freeid(struct tdx_td *td)
 
 	return seamcall(TDH_MNG_KEY_FREEID, &args);
 }
-EXPORT_SYMBOL_GPL(tdh_mng_key_freeid);
+EXPORT_SYMBOL_FOR_KVM(tdh_mng_key_freeid);
 
 u64 tdh_mng_init(struct tdx_td *td, u64 td_params, u64 *extended_err)
 {
@@ -1744,7 +1745,7 @@ u64 tdh_mng_init(struct tdx_td *td, u64 td_params, u64 *extended_err)
 
 	return ret;
 }
-EXPORT_SYMBOL_GPL(tdh_mng_init);
+EXPORT_SYMBOL_FOR_KVM(tdh_mng_init);
 
 u64 tdh_vp_rd(struct tdx_vp *vp, u64 field, u64 *data)
 {
@@ -1761,7 +1762,7 @@ u64 tdh_vp_rd(struct tdx_vp *vp, u64 field, u64 *data)
 
 	return ret;
 }
-EXPORT_SYMBOL_GPL(tdh_vp_rd);
+EXPORT_SYMBOL_FOR_KVM(tdh_vp_rd);
 
 u64 tdh_vp_wr(struct tdx_vp *vp, u64 field, u64 data, u64 mask)
 {
@@ -1774,7 +1775,7 @@ u64 tdh_vp_wr(struct tdx_vp *vp, u64 field, u64 data, u64 mask)
 
 	return seamcall(TDH_VP_WR, &args);
 }
-EXPORT_SYMBOL_GPL(tdh_vp_wr);
+EXPORT_SYMBOL_FOR_KVM(tdh_vp_wr);
 
 u64 tdh_vp_init(struct tdx_vp *vp, u64 initial_rcx, u32 x2apicid)
 {
@@ -1787,7 +1788,7 @@ u64 tdh_vp_init(struct tdx_vp *vp, u64 initial_rcx, u32 x2apicid)
 	/* apicid requires version == 1. */
 	return seamcall(TDH_VP_INIT | (1ULL << TDX_VERSION_SHIFT), &args);
 }
-EXPORT_SYMBOL_GPL(tdh_vp_init);
+EXPORT_SYMBOL_FOR_KVM(tdh_vp_init);
 
 /*
  * TDX ABI defines output operands as PT, OWNER and SIZE. These are TDX defined fomats.
@@ -1809,7 +1810,7 @@ u64 tdh_phymem_page_reclaim(struct page *page, u64 *tdx_pt, u64 *tdx_owner, u64
 
 	return ret;
 }
-EXPORT_SYMBOL_GPL(tdh_phymem_page_reclaim);
+EXPORT_SYMBOL_FOR_KVM(tdh_phymem_page_reclaim);
 
 u64 tdh_mem_track(struct tdx_td *td)
 {
@@ -1819,7 +1820,7 @@ u64 tdh_mem_track(struct tdx_td *td)
 
 	return seamcall(TDH_MEM_TRACK, &args);
 }
-EXPORT_SYMBOL_GPL(tdh_mem_track);
+EXPORT_SYMBOL_FOR_KVM(tdh_mem_track);
 
 u64 tdh_mem_page_remove(struct tdx_td *td, u64 gpa, u64 level, u64 *ext_err1, u64 *ext_err2)
 {
@@ -1836,7 +1837,7 @@ u64 tdh_mem_page_remove(struct tdx_td *td, u64 gpa, u64 level, u64 *ext_err1, u6
 
 	return ret;
 }
-EXPORT_SYMBOL_GPL(tdh_mem_page_remove);
+EXPORT_SYMBOL_FOR_KVM(tdh_mem_page_remove);
 
 u64 tdh_phymem_cache_wb(bool resume)
 {
@@ -1846,7 +1847,7 @@ u64 tdh_phymem_cache_wb(bool resume)
 
 	return seamcall(TDH_PHYMEM_CACHE_WB, &args);
 }
-EXPORT_SYMBOL_GPL(tdh_phymem_cache_wb);
+EXPORT_SYMBOL_FOR_KVM(tdh_phymem_cache_wb);
 
 u64 tdh_phymem_page_wbinvd_tdr(struct tdx_td *td)
 {
@@ -1856,7 +1857,7 @@ u64 tdh_phymem_page_wbinvd_tdr(struct tdx_td *td)
 
 	return seamcall(TDH_PHYMEM_PAGE_WBINVD, &args);
 }
-EXPORT_SYMBOL_GPL(tdh_phymem_page_wbinvd_tdr);
+EXPORT_SYMBOL_FOR_KVM(tdh_phymem_page_wbinvd_tdr);
 
 u64 tdh_phymem_page_wbinvd_hkid(u64 hkid, struct page *page)
 {
@@ -1866,7 +1867,7 @@ u64 tdh_phymem_page_wbinvd_hkid(u64 hkid, struct page *page)
 
 	return seamcall(TDH_PHYMEM_PAGE_WBINVD, &args);
 }
-EXPORT_SYMBOL_GPL(tdh_phymem_page_wbinvd_hkid);
+EXPORT_SYMBOL_FOR_KVM(tdh_phymem_page_wbinvd_hkid);
 
 #ifdef CONFIG_KEXEC_CORE
 void tdx_cpu_flush_cache_for_kexec(void)
@@ -1884,5 +1885,5 @@ void tdx_cpu_flush_cache_for_kexec(void)
 	wbinvd();
 	this_cpu_write(cache_state_incoherent, false);
 }
-EXPORT_SYMBOL_GPL(tdx_cpu_flush_cache_for_kexec);
+EXPORT_SYMBOL_FOR_KVM(tdx_cpu_flush_cache_for_kexec);
 #endif