On Wed, Sep 10, 2025, Ashish Kalra wrote:
> diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
> index 00475b814ac4..7a1ae990b15f 100644
> --- a/arch/x86/include/asm/sev.h
> +++ b/arch/x86/include/asm/sev.h
> @@ -635,10 +635,15 @@ void snp_dump_hva_rmpentry(unsigned long address);
> int psmash(u64 pfn);
> int rmp_make_private(u64 pfn, u64 gpa, enum pg_level level, u32 asid, bool immutable);
> int rmp_make_shared(u64 pfn, enum pg_level level);
> -void snp_leak_pages(u64 pfn, unsigned int npages);
> +void __snp_leak_pages(u64 pfn, unsigned int npages, bool dump_rmp);
> void kdump_sev_callback(void);
> void snp_fixup_e820_tables(void);
>
> +static inline void snp_leak_pages(u64 pfn, unsigned int pages)
> +{
> + __snp_leak_pages(pfn, pages, true);
> +}
> +
> static inline void sev_evict_cache(void *va, int npages)
> {
> volatile u8 val __always_unused;
> @@ -668,6 +673,7 @@ static inline int rmp_make_private(u64 pfn, u64 gpa, enum pg_level level, u32 as
> return -ENODEV;
> }
> static inline int rmp_make_shared(u64 pfn, enum pg_level level) { return -ENODEV; }
> +static inline void __snp_leak_pages(u64 pfn, unsigned int npages, bool dump_rmp) {}
This stub is unnecessary. As pointed out elsewhere[*], I'm pretty sure all these
stubs are unnecessary.
Oof. Even worse, the stubs appear to be actively hiding bugs. The APIs are
guarded with CONFIG_KVM_AMD_SEV=y, but **KVM** doesn't call any of these outside
of SEV code. I.e. if *KVM* were the only user, the stubs would just be dead code.
But the below build failures show that they aren't dead code, which means that
kernels with CONFIG_KVM_AMD_SEV=n will silently (until something explodes) do the
wrong thing, because the stubs are hiding the missing dependencies.
arch/x86/boot/startup/sev-shared.c: In function ‘pvalidate_4k_page’:
arch/x86/boot/startup/sev-shared.c:820:17: error: implicit declaration of function ‘sev_evict_cache’ [-Wimplicit-function-declaration]
820 | sev_evict_cache((void *)vaddr, 1);
| ^~~~~~~~~~~~~~~
AR arch/x86/realmode/built-in.a
arch/x86/coco/sev/core.c: In function ‘pvalidate_pages’:
arch/x86/coco/sev/core.c:386:25: error: implicit declaration of function ‘sev_evict_cache’ [-Wimplicit-function-declaration]
386 | sev_evict_cache(pfn_to_kaddr(e->gfn), e->pagesize ? 512 : 1);
| ^~~~~~~~~~~~~~~
arch/x86/mm/mem_encrypt.c: In function ‘mem_encrypt_setup_arch’:
arch/x86/mm/mem_encrypt.c:112:17: error: implicit declaration of function ‘snp_fixup_e820_tables’ [-Wimplicit-function-declaration]
112 | snp_fixup_e820_tables();
| ^~~~~~~~~~~~~~~~~~~~~
arch/x86/mm/fault.c: In function ‘show_fault_oops’:
arch/x86/mm/fault.c:587:17: error: implicit declaration of function ‘snp_dump_hva_rmpentry’ [-Wimplicit-function-declaration]
587 | snp_dump_hva_rmpentry(address);
| ^~~~~~~~~~~~~~~~~~~~~
arch/x86/kernel/cpu/amd.c: In function ‘bsp_determine_snp’:
arch/x86/kernel/cpu/amd.c:370:21: error: implicit declaration of function ‘snp_probe_rmptable_info’ [-Wimplicit-function-declaration]
370 | snp_probe_rmptable_info()) {
| ^~~~~~~~~~~~~~~~~~~~~~~
AR drivers/iommu/amd/built-in.a
AR drivers/iommu/built-in.a
AR drivers/built-in.a
[*] https://lore.kernel.org/all/aMHP5EO-ucJGdHXz@xxxxxxxxxx
