lkml.org 
[lkml]   [2020]   [Mar]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v6 14/14] KVM: x86: Add kexec support for SEV Live Migration.
From
Date

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@amd.com>
>>>
>>> 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@amd.com>
>>> ---
>>> 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.


>>> + 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

\
 
 \ /
  Last update: 2020-03-31 16:27    [W:0.126 / U:0.088 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site