Commit 9c016c3f authored by Tom Lendacky's avatar Tom Lendacky Committed by Borislav Petkov (AMD)
Browse files

x86/sev: Create a function to clear/zero the RMP 



In preparation for delayed SNP initialization and disablement on shutdown,
create a function, clear_rmp(), that clears the RMP bookkeeping area and the
RMP entries.

Signed-off-by: default avatarTom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: default avatarTycho Andersen (AMD) <tycho@kernel.org>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Link: https://patch.msgid.link/20260324161301.1353976-2-tycho@kernel.org
parent 531397a8

arch/x86/virt/svm/sev.c

+27 −14
Original line number Diff line number Diff line
@@ -242,6 +242,32 @@ void __init snp_fixup_e820_tables(void) 
	}

}



static void clear_rmp(void)

{

	unsigned int i;

	u64 val;



	if (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))

		return;



	/* Clearing the RMP while SNP is enabled will cause an exception */

	rdmsrq(MSR_AMD64_SYSCFG, val);

	if (WARN_ON_ONCE(val & MSR_AMD64_SYSCFG_SNP_EN))

		return;



	memset(rmp_bookkeeping, 0, RMPTABLE_CPU_BOOKKEEPING_SZ);



	for (i = 0; i < rst_max_index; i++) {

		struct rmp_segment_desc *desc;



		desc = rmp_segment_table[i];

		if (!desc)

			continue;



		memset(desc->rmp_entry, 0, desc->size);

	}

}



static bool __init alloc_rmp_segment_desc(u64 segment_pa, u64 segment_size, u64 pa)

{

	u64 rst_index, rmp_segment_size_max;
@@ -484,7 +510,6 @@ static bool __init setup_rmptable(void) 
 */

int __init snp_rmptable_init(void)

{

	unsigned int i;

	u64 val;



	if (WARN_ON_ONCE(!cc_platform_has(CC_ATTR_HOST_SEV_SNP)))
@@ -504,19 +529,7 @@ int __init snp_rmptable_init(void) 
	if (val & MSR_AMD64_SYSCFG_SNP_EN)

		goto skip_enable;



	/* Zero out the RMP bookkeeping area */

	memset(rmp_bookkeeping, 0, RMPTABLE_CPU_BOOKKEEPING_SZ);



	/* Zero out the RMP entries */

	for (i = 0; i < rst_max_index; i++) {

		struct rmp_segment_desc *desc;



		desc = rmp_segment_table[i];

		if (!desc)

			continue;



		memset(desc->rmp_entry, 0, desc->size);

	}

	clear_rmp();



	/* MtrrFixDramModEn must be enabled on all the CPUs prior to enabling SNP. */

	on_each_cpu(mfd_enable, NULL, 1);