x86/sev: Add new dump_rmp parameter to snp_leak_pages() API

When leaking certain page types, such as Hypervisor Fixed (HV_FIXED)
pages, it does not make sense to dump RMP contents for the 2MB range of
the page(s) being leaked. In the case of HV_FIXED pages, this is not an
error situation where the surrounding 2MB page RMP entries can provide
debug information.

Add new __snp_leak_pages() API with dump_rmp bool parameter to support
continue adding pages to the snp_leaked_pages_list but not issue
dump_rmpentry().

Make snp_leak_pages() a wrapper for the common case which also allows
existing users to continue to dump RMP entries.

Suggested-by: Thomas Lendacky <Thomas.Lendacky@amd.com>
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Acked-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/cover.1758057691.git.ashish.kalra@amd.com

Author: ashkalra

arch/x86/include/asm/sev.h

@@ -655,9 +655,13 @@ 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);
+}
 #else
 static inline bool snp_probe_rmptable_info(void) { return false; }
 static inline int snp_rmptable_init(void) { return -ENOSYS; }
@@ -670,6 +674,7 @@ 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) {}
 static inline void snp_leak_pages(u64 pfn, unsigned int npages) {}
 static inline void kdump_sev_callback(void) { }
 static inline void snp_fixup_e820_tables(void) {}

arch/x86/virt/svm/sev.c

@@ -1029,7 +1029,7 @@ int rmp_make_shared(u64 pfn, enum pg_level level)
 }
 EXPORT_SYMBOL_GPL(rmp_make_shared);
 
-void snp_leak_pages(u64 pfn, unsigned int npages)
+void __snp_leak_pages(u64 pfn, unsigned int npages, bool dump_rmp)
 {
 	struct page *page = pfn_to_page(pfn);
 
@@ -1052,14 +1052,15 @@ void snp_leak_pages(u64 pfn, unsigned int npages)
 		    (PageHead(page) && compound_nr(page) <= npages))
 			list_add_tail(&page->buddy_list, &snp_leaked_pages_list);
 
-		dump_rmpentry(pfn);
+		if (dump_rmp)
+			dump_rmpentry(pfn);
 		snp_nr_leaked_pages++;
 		pfn++;
 		page++;
 	}
 	spin_unlock(&snp_leaked_pages_list_lock);
 }
-EXPORT_SYMBOL_GPL(snp_leak_pages);
+EXPORT_SYMBOL_GPL(__snp_leak_pages);
 
 void kdump_sev_callback(void)
 {