Hello Brijesh,
On Tue, Mar 31, 2020 at 09:26:26AM -0500, Brijesh Singh wrote:
>
> On 3/30/20 11:45 AM, Ashish Kalra wrote:
> > Hello Brijesh,
> >
> > On Mon, Mar 30, 2020 at 11:00:14AM -0500, Brijesh Singh wrote:
> >> On 3/30/20 1:23 AM, Ashish Kalra wrote:
> >>> From: Ashish Kalra <ashish.kalra@xxxxxxx>
> >>>
> >>> Reset the host's page encryption bitmap related to kernel
> >>> specific page encryption status settings before we load a
> >>> new kernel by kexec. We cannot reset the complete
> >>> page encryption bitmap here as we need to retain the
> >>> UEFI/OVMF firmware specific settings.
> >>>
> >>> Signed-off-by: Ashish Kalra <ashish.kalra@xxxxxxx>
> >>> ---
> >>> arch/x86/kernel/kvm.c | 28 ++++++++++++++++++++++++++++
> >>> 1 file changed, 28 insertions(+)
> >>>
> >>> diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
> >>> index 8fcee0b45231..ba6cce3c84af 100644
> >>> --- a/arch/x86/kernel/kvm.c
> >>> +++ b/arch/x86/kernel/kvm.c
> >>> @@ -34,6 +34,7 @@
> >>> #include <asm/hypervisor.h>
> >>> #include <asm/tlb.h>
> >>> #include <asm/cpuidle_haltpoll.h>
> >>> +#include <asm/e820/api.h>
> >>>
> >>> static int kvmapf = 1;
> >>>
> >>> @@ -357,6 +358,33 @@ static void kvm_pv_guest_cpu_reboot(void *unused)
> >>> */
> >>> if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
> >>> wrmsrl(MSR_KVM_PV_EOI_EN, 0);
> >>> + /*
> >>> + * Reset the host's page encryption bitmap related to kernel
> >>> + * specific page encryption status settings before we load a
> >>> + * new kernel by kexec. NOTE: We cannot reset the complete
> >>> + * page encryption bitmap here as we need to retain the
> >>> + * UEFI/OVMF firmware specific settings.
> >>> + */
> >>> + if (kvm_para_has_feature(KVM_FEATURE_SEV_LIVE_MIGRATION) &&
> >>> + (smp_processor_id() == 0)) {
> >>
> >> In patch 13/14, the KVM_FEATURE_SEV_LIVE_MIGRATION is set
> >> unconditionally and because of that now the below code will be executed
> >> on non-SEV guest. IMO, this feature must be cleared for non-SEV guest to
> >> avoid making unnecessary hypercall's.
> >>
> >>
> > I will additionally add a sev_active() check here to ensure that we don't make the unnecassary hypercalls on non-SEV guests.
>
>
> IMO, instead of using the sev_active() we should make sure that the
> feature is not enabled when SEV is not active.
>
Yes, now the KVM_FEATURE_SEV_LIVE_MIGRATION feature is enabled
dynamically in svm_cpuid_update() after it gets called from
svm_launch_finish(), which ensures that it only gets set when a SEV
guest is active.
Thanks,
Ashish
>
> >>> + unsigned long nr_pages;
> >>> + int i;
> >>> +
> >>> + for (i = 0; i < e820_table->nr_entries; i++) {
> >>> + struct e820_entry *entry = &e820_table->entries[i];
> >>> + unsigned long start_pfn, end_pfn;
> >>> +
> >>> + if (entry->type != E820_TYPE_RAM)
> >>> + continue;
> >>> +
> >>> + start_pfn = entry->addr >> PAGE_SHIFT;
> >>> + end_pfn = (entry->addr + entry->size) >> PAGE_SHIFT;
> >>> + nr_pages = DIV_ROUND_UP(entry->size, PAGE_SIZE);
> >>> +
> >>> + kvm_sev_hypercall3(KVM_HC_PAGE_ENC_STATUS,
> >>> + entry->addr, nr_pages, 1);
> >>> + }
> >>> + }
> >>> kvm_pv_disable_apf();
> >>> kvm_disable_steal_time();
> >>> }
> > Thanks,
> > Ashish
