github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-05-28 09:04:39 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

x86/virt/sev: Drop support for SNP hotplug

Browse Source 
During an SNP_INIT(_EX), the SEV firmware checks that all CPUs have the SNP
syscfg bit set, and fails if they do not. As such, it does not make
sense to have offline CPUs: the firmware will fail initialization because
of the offlined ones that the kernel did not initialize.

Further, there is a bug: during SNP_INIT(_EX) the firmware requires the MFDM
syscfg bit to be set in addition to having SNP enabled, which the previous
hotplug code did not do. Since k8_check_syscfg_dram_mod_en() enforces this
be cleared, hotplug wouldn't work.

Signed-off-by: Tycho Andersen (AMD) <tycho@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Link: https://patch.msgid.link/20260309180053.2389118-2-tycho@kernel.org
This commit is contained in:
Tycho Andersen (AMD) 2026-03-09 12:00:43 -06:00 committed by Borislav Petkov (AMD)
parent 1f318b96cc
commit 959d3f7565
1 changed files with 6 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

34
arch/x86/virt/svm/sev.c
View File

@ -130,33 +130,20 @@ static unsigned long snp_nr_leaked_pages;
#undef pr_fmt
#define pr_fmt(fmt) "SEV-SNP: " fmt
static int __mfd_enable(unsigned int cpu)
{
u64 val;
if (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))
return 0;
rdmsrq(MSR_AMD64_SYSCFG, val);
val |= MSR_AMD64_SYSCFG_MFDM;
wrmsrq(MSR_AMD64_SYSCFG, val);
return 0;
}
static __init void mfd_enable(void *arg)
{
__mfd_enable(smp_processor_id());
if (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))
return;
msr_set_bit(MSR_AMD64_SYSCFG, MSR_AMD64_SYSCFG_MFDM_BIT);
}
static int __snp_enable(unsigned int cpu)
static __init void snp_enable(void *arg)
{
u64 val;
if (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))
return 0;
return;
rdmsrq(MSR_AMD64_SYSCFG, val);
@ -164,13 +151,6 @@ static int __snp_enable(unsigned int cpu)
val |= MSR_AMD64_SYSCFG_SNP_VMPL_EN;
wrmsrq(MSR_AMD64_SYSCFG, val);
return 0;
}
static __init void snp_enable(void *arg)
{
__snp_enable(smp_processor_id());
}
static void __init __snp_fixup_e820_tables(u64 pa)
@ -553,8 +533,6 @@ int __init snp_rmptable_init(void)
on_each_cpu(snp_enable, NULL, 1);
skip_enable:
cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/rmptable_init:online", __snp_enable, NULL);
/*
* Setting crash_kexec_post_notifiers to 'true' to ensure that SNP panic
* notifier is invoked to do SNP IOMMU shutdown before kdump.