Hello Sean,
On 1/30/2025 7:41 PM, Sean Christopherson wrote:
> On Fri, Jan 31, 2025, Ashish Kalra wrote:
>> From: Ashish Kalra <ashish.kalra@xxxxxxx>
>>
>> This patch fixes issues with enabling SNP host support and effectively
> ^^^^^^^^^^
>
>> ---
>> arch/x86/include/asm/sev.h | 2 ++
>> arch/x86/virt/svm/sev.c | 23 +++++++----------------
>> 2 files changed, 9 insertions(+), 16 deletions(-)
>>
>> diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
>> index 5d9685f92e5c..1581246491b5 100644
>> --- a/arch/x86/include/asm/sev.h
>> +++ b/arch/x86/include/asm/sev.h
>> @@ -531,6 +531,7 @@ static inline void __init snp_secure_tsc_init(void) { }
>>
>> #ifdef CONFIG_KVM_AMD_SEV
>> bool snp_probe_rmptable_info(void);
>> +int snp_rmptable_init(void);
>> int snp_lookup_rmpentry(u64 pfn, bool *assigned, int *level);
>> void snp_dump_hva_rmpentry(unsigned long address);
>> int psmash(u64 pfn);
>> @@ -541,6 +542,7 @@ void kdump_sev_callback(void);
>> void snp_fixup_e820_tables(void);
>> #else
>> static inline bool snp_probe_rmptable_info(void) { return false; }
>> +static inline int snp_rmptable_init(void) { return -ENOSYS; }
>> static inline int snp_lookup_rmpentry(u64 pfn, bool *assigned, int *level) { return -ENODEV; }
>> static inline void snp_dump_hva_rmpentry(unsigned long address) {}
>> static inline int psmash(u64 pfn) { return -ENODEV; }
>> diff --git a/arch/x86/virt/svm/sev.c b/arch/x86/virt/svm/sev.c
>> index 1dcc027ec77e..42e74a5a7d78 100644
>> --- a/arch/x86/virt/svm/sev.c
>> +++ b/arch/x86/virt/svm/sev.c
>> @@ -505,19 +505,19 @@ static bool __init setup_rmptable(void)
>> * described in the SNP_INIT_EX firmware command description in the SNP
>> * firmware ABI spec.
>> */
>> -static int __init snp_rmptable_init(void)
>> +int __init snp_rmptable_init(void)
>> {
>> unsigned int i;
>> u64 val;
>>
>> - if (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))
>> - return 0;
>> + if (WARN_ON_ONCE(!cc_platform_has(CC_ATTR_HOST_SEV_SNP)))
>> + return -ENOSYS;
>>
>> - if (!amd_iommu_snp_en)
>> - goto nosnp;
>> + if (WARN_ON_ONCE(!amd_iommu_snp_en))
>> + return -ENOSYS;
>>
>> if (!setup_rmptable())
>> - goto nosnp;
>> + return -ENOSYS;
>>
>> /*
>> * Check if SEV-SNP is already enabled, this can happen in case of
>> @@ -530,7 +530,7 @@ static int __init snp_rmptable_init(void)
>> /* Zero out the RMP bookkeeping area */
>> if (!clear_rmptable_bookkeeping()) {
>> free_rmp_segment_table();
>> - goto nosnp;
>> + return -ENOSYS;
>> }
>>
>> /* Zero out the RMP entries */
>> @@ -562,17 +562,8 @@ static int __init snp_rmptable_init(void)
>> crash_kexec_post_notifiers = true;
>>
>> return 0;
>> -
>> -nosnp:
>> - cc_platform_clear(CC_ATTR_HOST_SEV_SNP);
>> - return -ENOSYS;
>> }
>>
>> -/*
>> - * This must be called after the IOMMU has been initialized.
>> - */
>> -device_initcall(snp_rmptable_init);
>
> There's the wee little problem that snp_rmptable_init() is never called as of
> this patch. Dropping the device_initcall() needs to happen in the same patch
> that wires up the IOMMU code to invoke snp_rmptable_init().
The issue with that is the IOMMU and x86 maintainers are different, so i believe that we will
need to split the dropping of device_initcall() in platform code and the code to wire up the
IOMMU driver to invoke snp_rmptable_init(), to get the patch merged in different trees ?
>At a glance, I don't see anything in this patch that can reasonably go in before the IOMMU change.
This patch prepares snp_rmptable_init() to be called via iommu_snp_enable(), so i assume this
is a pre-patch before the IOMMU change.
Thanks,
Ashish
