x86/sev: Ensure SVSM reserved fields in a page validation entry are initialized to zero

In order to support future versions of the SVSM_CORE_PVALIDATE call, all
reserved fields within a PVALIDATE entry must be set to zero as an SVSM should
be ensuring all reserved fields are zero in order to support future usage of
reserved areas based on the protocol version.

Fixes: fcd042e ("x86/sev: Perform PVALIDATE using the SVSM when not at VMPL0")
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Joerg Roedel <joerg.roedel@amd.com>
Cc: <stable@kernel.org>
Link: https://lore.kernel.org/7cde412f8b057ea13a646fb166b1ca023f6a5031.1755098819.git.thomas.lendacky@amd.com

Author: tlendacky

arch/x86/boot/startup/sev-shared.c

@@ -785,6 +785,7 @@ static void __head svsm_pval_4k_page(unsigned long paddr, bool validate)
 	pc->entry[0].page_size = RMP_PG_SIZE_4K;
 	pc->entry[0].action    = validate;
 	pc->entry[0].ignore_cf = 0;
+	pc->entry[0].rsvd      = 0;
 	pc->entry[0].pfn       = paddr >> PAGE_SHIFT;
 
 	/* Protocol 0, Call ID 1 */

arch/x86/coco/sev/core.c

@@ -227,6 +227,7 @@ static u64 svsm_build_ca_from_pfn_range(u64 pfn, u64 pfn_end, bool action,
 		pe->page_size = RMP_PG_SIZE_4K;
 		pe->action    = action;
 		pe->ignore_cf = 0;
+		pe->rsvd      = 0;
 		pe->pfn       = pfn;
 
 		pe++;
@@ -257,6 +258,7 @@ static int svsm_build_ca_from_psc_desc(struct snp_psc_desc *desc, unsigned int d
 		pe->page_size = e->pagesize ? RMP_PG_SIZE_2M : RMP_PG_SIZE_4K;
 		pe->action    = e->operation == SNP_PAGE_STATE_PRIVATE;
 		pe->ignore_cf = 0;
+		pe->rsvd      = 0;
 		pe->pfn       = e->gfn;
 
 		pe++;