Messages in this thread | | | From | Paolo Bonzini <> | Subject | Re: [PATCH v13 12/12] x86/kvm: Add guest support for detecting and enabling SEV Live Migration feature. | Date | Wed, 21 Apr 2021 17:38:45 +0200 |
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On 21/04/21 16:44, Borislav Petkov wrote: > On Thu, Apr 15, 2021 at 04:01:16PM +0000, Ashish Kalra wrote: >> From: Ashish Kalra <ashish.kalra@amd.com> >> >> The guest support for detecting and enabling SEV Live migration >> feature uses the following logic : >> >> - kvm_init_plaform() invokes check_kvm_sev_migration() which >> checks if its booted under the EFI >> >> - If not EFI, >> >> i) check for the KVM_FEATURE_CPUID > > Where do you do that? > > $ git grep KVM_FEATURE_CPUID > $ > > Do you mean > > kvm_para_has_feature(KVM_FEATURE_SEV_LIVE_MIGRATION) > > per chance?
Yep. Or KVM_CPUID_FEATURES perhaps.
> >> diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c >> index 78bb0fae3982..94ef16d263a7 100644 >> --- a/arch/x86/kernel/kvm.c >> +++ b/arch/x86/kernel/kvm.c >> @@ -26,6 +26,7 @@ >> #include <linux/kprobes.h> >> #include <linux/nmi.h> >> #include <linux/swait.h> >> +#include <linux/efi.h> >> #include <asm/timer.h> >> #include <asm/cpu.h> >> #include <asm/traps.h> >> @@ -429,6 +430,59 @@ static inline void __set_percpu_decrypted(void *ptr, unsigned long size) >> early_set_memory_decrypted((unsigned long) ptr, size); >> } >> >> +static int __init setup_kvm_sev_migration(void) > > kvm_init_sev_migration() or so. > > ... > >> @@ -48,6 +50,8 @@ EXPORT_SYMBOL_GPL(sev_enable_key); >> >> bool sev_enabled __section(".data"); >> >> +bool sev_live_migration_enabled __section(".data"); > > Pls add a function called something like: > > bool sev_feature_enabled(enum sev_feature) > > and gets SEV_FEATURE_LIVE_MIGRATION and then use it instead of adding > yet another boolean which contains whether some aspect of SEV has been > enabled or not. > > Then add a > > static enum sev_feature sev_features; > > in mem_encrypt.c and that function above will query that sev_features > enum for set flags.
Even better: let's stop callings things SEV/SEV_ES. Long term we want anyway to use things like mem_encrypt_enabled (SEV), guest_instruction_trap_enabled (SEV/ES), etc.
For this one we don't need a bool at all, we can simply check whether the pvop points to paravirt_nop. Also keep everything but the BSS handling in arch/x86/kernel/kvm.c. Only the BSS handling should be in arch/x86/mm/mem_encrypt.c. This way all KVM paravirt hypercalls and MSRs are in kvm.c.
That is:
void kvm_init_platform(void) { if (sev_active() && kvm_para_has_feature(KVM_FEATURE_SEV_LIVE_MIGRATION)) { pv_ops.mmu.notify_page_enc_status_changed = kvm_sev_hc_page_enc_status; /* this takes care of bss_decrypted */ early_set_page_enc_status(); if (!efi_enabled(EFI_BOOT)) wrmsrl(MSR_KVM_SEV_LIVE_MIGRATION, KVM_SEV_LIVE_MIGRATION_ENABLED); } /* existing kvm_init_platform code goes here */ }
// the pvop is changed to take the pfn, so that the vaddr loop // is not KVM specific static inline void notify_page_enc_status_changed(unsigned long pfn, int npages, bool enc) { PVOP_VCALL3(mmu.page_encryption_changed, pfn, npages, enc); }
static void notify_addr_enc_status_changed(unsigned long addr, int numpages, bool enc) { #ifdef CONFIG_PARAVIRT if (pv_ops.mmu.notify_page_enc_status_changed == paravirt_nop) return;
/* the body of set_memory_enc_dec_hypercall goes here */ for (; vaddr < vaddr_end; vaddr = vaddr_next) { ... notify_page_enc_status_changed(pfn, psize >> PAGE_SHIFT, enc); vaddr_next = (vaddr & pmask) + psize; } #endif }
static int __set_memory_enc_dec(unsigned long addr, int numpages, bool enc) { ... cpa_flush(&cpa, 0); notify_addr_enc_status_changed(addr, numpages, enc); return ret; }
> +static int __init setup_kvm_sev_migration(void)
Please rename this to include efi in the function name.
> > + */ > + if (!efi_enabled(EFI_BOOT)) > + wrmsrl(MSR_KVM_SEV_LIVE_MIGRATION, > + KVM_SEV_LIVE_MIGRATION_ENABLED); > + } else { > + pr_info("KVM enable live migration feature unsupported\n"); > + } > +}
I think this pr_info is incorrect, because it can still be enabled in the late_initcall. Just remove it as in the sketch above.
Paolo
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