RE: [PATCH] KVM: SVM: Use a separate vmcb for the nested L2 guest

From: Babu Moger
Date: Fri Sep 18 2020 - 12:47:02 EST

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> -----Original Message-----
> From: Cathy Avery <cavery@xxxxxxxxxx>
> Sent: Friday, September 18, 2020 10:27 AM
> To: Moger, Babu <Babu.Moger@xxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx;
> kvm@xxxxxxxxxxxxxxx; pbonzini@xxxxxxxxxx
> Cc: vkuznets@xxxxxxxxxx; Huang2, Wei <Wei.Huang2@xxxxxxx>
> Subject: Re: [PATCH] KVM: SVM: Use a separate vmcb for the nested L2 guest
>
> On 9/18/20 11:16 AM, Babu Moger wrote:
> > Cathy,
> > Thanks for the patches. It cleans up the code nicely.
> > But there are some issues with the patch. I was able to bring the L1
> > guest with your patch. But when I tried to load L2 guest it crashed. I
> > am thinking It is mostly due to save/restore part of vmcb. Few comments
> below.
> >
> >> -----Original Message-----
> >> From: Cathy Avery <cavery@xxxxxxxxxx>
> >> Sent: Thursday, September 17, 2020 2:23 PM
> >> To: linux-kernel@xxxxxxxxxxxxxxx; kvm@xxxxxxxxxxxxxxx;
> >> pbonzini@xxxxxxxxxx
> >> Cc: vkuznets@xxxxxxxxxx; Huang2, Wei <Wei.Huang2@xxxxxxx>
> >> Subject: [PATCH] KVM: SVM: Use a separate vmcb for the nested L2
> >> guest
> >>
> >> svm->vmcb will now point to either a separate vmcb L1 ( not nested )
> >> svm->or L2 vmcb
> >> ( nested ).
> >>
> >> Issues:
> >>
> >> 1) There is some wholesale copying of vmcb.save and vmcb.contol
> >> areas which will need to be refined.
> >>
> >> 2) There is a workaround in nested_svm_vmexit() where
> >>
> >> if (svm->vmcb01->control.asid == 0)
> >> svm->vmcb01->control.asid = svm->nested.vmcb02->control.asid;
> >>
> >> This was done as a result of the kvm selftest 'state_test'. In that
> >> test svm_set_nested_state() is called before svm_vcpu_run().
> >> The asid is assigned by svm_vcpu_run -> pre_svm_run for the current
> >> vmcb which is now vmcb02 as we are in nested mode subsequently
> >> vmcb01.control.asid is never set as it should be.
> >>
> >> Tested:
> >> kvm-unit-tests
> >> kvm self tests
> >>
> >> Signed-off-by: Cathy Avery <cavery@xxxxxxxxxx>
> >> ---
> >> arch/x86/kvm/svm/nested.c | 116 ++++++++++++++++++--------------------
> >> arch/x86/kvm/svm/svm.c | 41 +++++++-------
> >> arch/x86/kvm/svm/svm.h | 10 ++--
> >> 3 files changed, 81 insertions(+), 86 deletions(-)
> >>
> >> diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
> >> index
> >> e90bc436f584..0a06e62010d8 100644
> >> --- a/arch/x86/kvm/svm/nested.c
> >> +++ b/arch/x86/kvm/svm/nested.c
> >> @@ -75,12 +75,12 @@ static unsigned long
> >> nested_svm_get_tdp_cr3(struct kvm_vcpu *vcpu) static void
> >> nested_svm_init_mmu_context(struct kvm_vcpu
> >> *vcpu) {
> >> struct vcpu_svm *svm = to_svm(vcpu);
> >> - struct vmcb *hsave = svm->nested.hsave;
> >>
> >> WARN_ON(mmu_is_nested(vcpu));
> >>
> >> vcpu->arch.mmu = &vcpu->arch.guest_mmu;
> >> - kvm_init_shadow_npt_mmu(vcpu, X86_CR0_PG, hsave->save.cr4,
> >> hsave->save.efer,
> >> + kvm_init_shadow_npt_mmu(vcpu, X86_CR0_PG, svm->vmcb01-
> >>> save.cr4,
> >> + svm->vmcb01->save.efer,
> >> svm->nested.ctl.nested_cr3);
> >> vcpu->arch.mmu->get_guest_pgd = nested_svm_get_tdp_cr3;
> >> vcpu->arch.mmu->get_pdptr = nested_svm_get_tdp_pdptr;
> >> @@ -105,7 +105,7 @@ void recalc_intercepts(struct vcpu_svm *svm)
> >> return;
> >>
> >> c = &svm->vmcb->control;
> >> - h = &svm->nested.hsave->control;
> >> + h = &svm->vmcb01->control;
> >> g = &svm->nested.ctl;
> >>
> >> svm->nested.host_intercept_exceptions = h->intercept_exceptions;
> >> @@ -403,7 +403,7 @@ static void nested_prepare_vmcb_control(struct
> >> vcpu_svm *svm)
> >>
> >> svm->vmcb->control.int_ctl =
> >> (svm->nested.ctl.int_ctl & ~mask) |
> >> - (svm->nested.hsave->control.int_ctl & mask);
> >> + (svm->vmcb01->control.int_ctl & mask);
> >>
> >> svm->vmcb->control.virt_ext = svm->nested.ctl.virt_ext;
> >> svm->vmcb->control.int_vector = svm->nested.ctl.int_vector;
> >> @@ -432,6 +432,12 @@ int enter_svm_guest_mode(struct vcpu_svm *svm,
> >> u64 vmcb_gpa,
> >> int ret;
> >>
> >> svm->nested.vmcb = vmcb_gpa;
> >> +
> >> + WARN_ON(svm->vmcb == svm->nested.vmcb02);
> >> +
> >> + svm->nested.vmcb02->control = svm->vmcb01->control;
> >> + svm->vmcb = svm->nested.vmcb02;
> >> + svm->vmcb_pa = svm->nested.vmcb02_pa;
> >> load_nested_vmcb_control(svm, &nested_vmcb->control);
> >> nested_prepare_vmcb_save(svm, nested_vmcb);
> >> nested_prepare_vmcb_control(svm);
> >> @@ -450,8 +456,6 @@ int nested_svm_vmrun(struct vcpu_svm *svm) {
> >> int ret;
> >> struct vmcb *nested_vmcb;
> >> - struct vmcb *hsave = svm->nested.hsave;
> >> - struct vmcb *vmcb = svm->vmcb;
> >> struct kvm_host_map map;
> >> u64 vmcb_gpa;
> >>
> >> @@ -496,29 +500,17 @@ int nested_svm_vmrun(struct vcpu_svm *svm)
> >> kvm_clear_exception_queue(&svm->vcpu);
> >> kvm_clear_interrupt_queue(&svm->vcpu);
> >>
> >> - /*
> >> - * Save the old vmcb, so we don't need to pick what we save, but can
> >> - * restore everything when a VMEXIT occurs
> >> - */
> >> - hsave->save.es = vmcb->save.es;
> >> - hsave->save.cs = vmcb->save.cs;
> >> - hsave->save.ss = vmcb->save.ss;
> >> - hsave->save.ds = vmcb->save.ds;
> >> - hsave->save.gdtr = vmcb->save.gdtr;
> >> - hsave->save.idtr = vmcb->save.idtr;
> >> - hsave->save.efer = svm->vcpu.arch.efer;
> >> - hsave->save.cr0 = kvm_read_cr0(&svm->vcpu);
> >> - hsave->save.cr4 = svm->vcpu.arch.cr4;
> >> - hsave->save.rflags = kvm_get_rflags(&svm->vcpu);
> >> - hsave->save.rip = kvm_rip_read(&svm->vcpu);
> >> - hsave->save.rsp = vmcb->save.rsp;
> >> - hsave->save.rax = vmcb->save.rax;
> >> - if (npt_enabled)
> >> - hsave->save.cr3 = vmcb->save.cr3;
> >> - else
> >> - hsave->save.cr3 = kvm_read_cr3(&svm->vcpu);
> >> -
> >> - copy_vmcb_control_area(&hsave->control, &vmcb->control);
> > You may have to carefully check the above cleanup.
> Thanks I'll check it out. I did not see a crash when running the tests. Could you
> send me more information about your test and test setup, stack trace, etc.

There is no stack trace. It basically does not load l2 guest.

1. Bare metal setup with RH 8.2(Any AMD EPYC system should be fine).
Download the latest kvm tree. Mine is kernel 5.9.0-rc1+your patch
# uname -r
5.9.0-rc1+
(You can actually just unload/load the kvm modules should also work.)

2. Now bring up the L1 guest on with the following command.
#qemu-system-x86_64 -name rhel8 -m 16384 -smp
cores=16,threads=1,sockets=1 -hda vdisk.qcow2 -enable-kvm -net nic -net
bridge,br=virbr0,helper=/usr/libexec/qem
u-bridge-helper -cpu EPYC -nographic

Download the latest kvm kernel on L1 guest. Mine is kernel
5.9.0-rc1+your patch
# uname -r
5.9.0-rc1+

3. Try to bring with the L2 guest with the following command.
#qemu-system-x86_64 -name rhel8 -m 16384 -smp
cores=16,threads=1,sockets=1 -hda vdisk.qcow2 -enable-kvm -net nic -net
bridge,br=virbr0,helper=/usr/libexec/qem
u-bridge-helper -cpu EPYC -nographic

L2 guest fails to start.

Note that L2 guest comes up fine without your patch.

Let me know if you need any more information. Thanks.

> >
> >> +
> >> + /* Update vmcb0. We will restore everything when a VMEXIT occurs */
> >> +
> >> + svm->vmcb01->save.efer = svm->vcpu.arch.efer;
> >> + svm->vmcb01->save.cr0 = kvm_read_cr0(&svm->vcpu);
> >> + svm->vmcb01->save.cr4 = svm->vcpu.arch.cr4;
> >> + svm->vmcb01->save.rflags = kvm_get_rflags(&svm->vcpu);
> >> + svm->vmcb01->save.rip = kvm_rip_read(&svm->vcpu);
> >> +
> >> + if (!npt_enabled)
> >> + svm->vmcb01->save.cr3 = kvm_read_cr3(&svm->vcpu);
> >>
> >> svm->nested.nested_run_pending = 1;
> >>
> >> @@ -564,7 +556,6 @@ int nested_svm_vmexit(struct vcpu_svm *svm) {
> >> int rc;
> >> struct vmcb *nested_vmcb;
> >> - struct vmcb *hsave = svm->nested.hsave;
> >> struct vmcb *vmcb = svm->vmcb;
> >> struct kvm_host_map map;
> >>
> >> @@ -628,8 +619,11 @@ int nested_svm_vmexit(struct vcpu_svm *svm)
> >> nested_vmcb->control.pause_filter_thresh =
> >> svm->vmcb->control.pause_filter_thresh;
> >>
> >> - /* Restore the original control entries */
> >> - copy_vmcb_control_area(&vmcb->control, &hsave->control);
> >> + if (svm->vmcb01->control.asid == 0)
> >> + svm->vmcb01->control.asid = svm->nested.vmcb02-
> >>> control.asid;
> >> +
> >> + svm->vmcb = svm->vmcb01;
> >> + svm->vmcb_pa = svm->nested.vmcb01_pa;
> >>
> >> /* On vmexit the GIF is set to false */
> >> svm_set_gif(svm, false);
> >> @@ -640,19 +634,13 @@ int nested_svm_vmexit(struct vcpu_svm *svm)
> >> svm->nested.ctl.nested_cr3 = 0;
> >>
> >> /* Restore selected save entries */
> >> - svm->vmcb->save.es = hsave->save.es;
> >> - svm->vmcb->save.cs = hsave->save.cs;
> >> - svm->vmcb->save.ss = hsave->save.ss;
> >> - svm->vmcb->save.ds = hsave->save.ds;
> >> - svm->vmcb->save.gdtr = hsave->save.gdtr;
> >> - svm->vmcb->save.idtr = hsave->save.idtr;
> >> - kvm_set_rflags(&svm->vcpu, hsave->save.rflags);
> >> - svm_set_efer(&svm->vcpu, hsave->save.efer);
> >> - svm_set_cr0(&svm->vcpu, hsave->save.cr0 | X86_CR0_PE);
> >> - svm_set_cr4(&svm->vcpu, hsave->save.cr4);
> >> - kvm_rax_write(&svm->vcpu, hsave->save.rax);
> >> - kvm_rsp_write(&svm->vcpu, hsave->save.rsp);
> >> - kvm_rip_write(&svm->vcpu, hsave->save.rip);
> >> + kvm_set_rflags(&svm->vcpu, svm->vmcb->save.rflags);
> >> + svm_set_efer(&svm->vcpu, svm->vmcb->save.efer);
> >> + svm_set_cr0(&svm->vcpu, svm->vmcb->save.cr0 | X86_CR0_PE);
> >> + svm_set_cr4(&svm->vcpu, svm->vmcb->save.cr4);
> >> + kvm_rax_write(&svm->vcpu, svm->vmcb->save.rax);
> >> + kvm_rsp_write(&svm->vcpu, svm->vmcb->save.rsp);
> >> + kvm_rip_write(&svm->vcpu, svm->vmcb->save.rip);
> >> svm->vmcb->save.dr7 = 0;
> >> svm->vmcb->save.cpl = 0;
> >> svm->vmcb->control.exit_int_info = 0; @@ -670,12 +658,12 @@ int
> >> nested_svm_vmexit(struct vcpu_svm *svm)
> >>
> >> nested_svm_uninit_mmu_context(&svm->vcpu);
> >>
> >> - rc = nested_svm_load_cr3(&svm->vcpu, hsave->save.cr3, false);
> >> + rc = nested_svm_load_cr3(&svm->vcpu, svm->vmcb->save.cr3, false);
> >> if (rc)
> >> return 1;
> >>
> >> - if (npt_enabled)
> >> - svm->vmcb->save.cr3 = hsave->save.cr3;
> >> + if (!npt_enabled)
> >> + svm->vmcb01->save.cr3 = kvm_read_cr3(&svm->vcpu);
> >>
> >> /*
> >> * Drop what we picked up for L2 via svm_complete_interrupts() so
> >> it @@ -694,12 +682,10 @@ int nested_svm_vmexit(struct vcpu_svm *svm)
> >> void svm_leave_nested(struct vcpu_svm *svm) {
> >> if (is_guest_mode(&svm->vcpu)) {
> >> - struct vmcb *hsave = svm->nested.hsave;
> >> - struct vmcb *vmcb = svm->vmcb;
> >> -
> >> svm->nested.nested_run_pending = 0;
> >> leave_guest_mode(&svm->vcpu);
> >> - copy_vmcb_control_area(&vmcb->control, &hsave->control);
> >> + svm->vmcb = svm->vmcb01;
> >> + svm->vmcb_pa = svm->nested.vmcb01_pa;
> >> nested_svm_uninit_mmu_context(&svm->vcpu);
> >> }
> >> }
> >> @@ -1046,10 +1032,9 @@ static int svm_get_nested_state(struct
> >> kvm_vcpu *vcpu,
> >> if (copy_to_user(&user_vmcb->control, &svm->nested.ctl,
> >> sizeof(user_vmcb->control)))
> >> return -EFAULT;
> >> - if (copy_to_user(&user_vmcb->save, &svm->nested.hsave->save,
> >> + if (copy_to_user(&user_vmcb->save, &svm->vmcb01->save,
> >> sizeof(user_vmcb->save)))
> >> return -EFAULT;
> >> -
> >> out:
> >> return kvm_state.size;
> >> }
> >> @@ -1059,7 +1044,6 @@ static int svm_set_nested_state(struct kvm_vcpu
> >> *vcpu,
> >> struct kvm_nested_state *kvm_state) {
> >> struct vcpu_svm *svm = to_svm(vcpu);
> >> - struct vmcb *hsave = svm->nested.hsave;
> >> struct vmcb __user *user_vmcb = (struct vmcb __user *)
> >> &user_kvm_nested_state->data.svm[0];
> >> struct vmcb_control_area ctl;
> >> @@ -1121,16 +1105,24 @@ static int svm_set_nested_state(struct
> >> kvm_vcpu *vcpu,
> >> if (!(save.cr0 & X86_CR0_PG))
> >> return -EINVAL;
> >>
> >> + svm->nested.vmcb02->control = svm->vmcb01->control;
> >> + svm->nested.vmcb02->save = svm->vmcb01->save;
> >> + svm->vmcb01->save = save;
> >> +
> >> + WARN_ON(svm->vmcb == svm->nested.vmcb02);
> >> +
> >> + svm->nested.vmcb = kvm_state->hdr.svm.vmcb_pa;
> >> +
> >> + svm->vmcb = svm->nested.vmcb02;
> >> + svm->vmcb_pa = svm->nested.vmcb02_pa;
> >> +
> >> /*
> >> - * All checks done, we can enter guest mode. L1 control fields
> >> - * come from the nested save state. Guest state is already
> >> - * in the registers, the save area of the nested state instead
> >> - * contains saved L1 state.
> >> + * All checks done, we can enter guest mode. L2 control fields will
> >> + * be the result of a combination of L1 and userspace indicated
> >> + * L12.control. The save area of L1 vmcb now contains the userspace
> >> + * indicated L1.save.
> >> */
> >> - copy_vmcb_control_area(&hsave->control, &svm->vmcb->control);
> >> - hsave->save = save;
> >>
> >> - svm->nested.vmcb = kvm_state->hdr.svm.vmcb_pa;
> >> load_nested_vmcb_control(svm, &ctl);
> >> nested_prepare_vmcb_control(svm);
> >>
> >> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index
> >> 5764b87379cf..d8022f989ffb 100644
> >> --- a/arch/x86/kvm/svm/svm.c
> >> +++ b/arch/x86/kvm/svm/svm.c
> >> @@ -971,8 +971,8 @@ static u64 svm_write_l1_tsc_offset(struct
> >> kvm_vcpu *vcpu, u64 offset)
> >> if (is_guest_mode(vcpu)) {
> >> /* Write L1's TSC offset. */
> >> g_tsc_offset = svm->vmcb->control.tsc_offset -
> >> - svm->nested.hsave->control.tsc_offset;
> >> - svm->nested.hsave->control.tsc_offset = offset;
> >> + svm->vmcb01->control.tsc_offset;
> >> + svm->vmcb01->control.tsc_offset = offset;
> >> }
> >>
> >> trace_kvm_write_tsc_offset(vcpu->vcpu_id,
> >> @@ -1171,9 +1171,9 @@ static void svm_vcpu_reset(struct kvm_vcpu
> >> *vcpu, bool init_event) static int svm_create_vcpu(struct kvm_vcpu *vcpu) {
> >> struct vcpu_svm *svm;
> >> - struct page *page;
> >> + struct page *vmcb01_page;
> >> + struct page *vmcb02_page;
> >> struct page *msrpm_pages;
> >> - struct page *hsave_page;
> >> struct page *nested_msrpm_pages;
> >> int err;
> >>
> >> @@ -1181,8 +1181,8 @@ static int svm_create_vcpu(struct kvm_vcpu *vcpu)
> >> svm = to_svm(vcpu);
> >>
> >> err = -ENOMEM;
> >> - page = alloc_page(GFP_KERNEL_ACCOUNT);
> >> - if (!page)
> >> + vmcb01_page = alloc_page(GFP_KERNEL_ACCOUNT);
> >> + if (!vmcb01_page)
> >> goto out;
> >>
> >> msrpm_pages = alloc_pages(GFP_KERNEL_ACCOUNT,
> MSRPM_ALLOC_ORDER);
> >> @@ -1193,8 +1193,8 @@ static int svm_create_vcpu(struct kvm_vcpu
> >> *vcpu)
> >> if (!nested_msrpm_pages)
> >> goto free_page2;
> >>
> >> - hsave_page = alloc_page(GFP_KERNEL_ACCOUNT);
> >> - if (!hsave_page)
> >> + vmcb02_page = alloc_page(GFP_KERNEL_ACCOUNT);
> >> + if (!vmcb02_page)
> >> goto free_page3;
> >>
> >> err = avic_init_vcpu(svm);
> >> @@ -1207,8 +1207,9 @@ static int svm_create_vcpu(struct kvm_vcpu *vcpu)
> >> if (irqchip_in_kernel(vcpu->kvm) && kvm_apicv_activated(vcpu->kvm))
> >> svm->avic_is_running = true;
> >>
> >> - svm->nested.hsave = page_address(hsave_page);
> >> - clear_page(svm->nested.hsave);
> >> + svm->nested.vmcb02 = page_address(vmcb02_page);
> >> + clear_page(svm->nested.vmcb02);
> >> + svm->nested.vmcb02_pa = __sme_set(page_to_pfn(vmcb02_page) <<
> >> +PAGE_SHIFT);
> >>
> >> svm->msrpm = page_address(msrpm_pages);
> >> svm_vcpu_init_msrpm(svm->msrpm);
> >> @@ -1216,9 +1217,11 @@ static int svm_create_vcpu(struct kvm_vcpu
> *vcpu)
> >> svm->nested.msrpm = page_address(nested_msrpm_pages);
> >> svm_vcpu_init_msrpm(svm->nested.msrpm);
> >>
> >> - svm->vmcb = page_address(page);
> >> + svm->vmcb = svm->vmcb01 = page_address(vmcb01_page);
> >> clear_page(svm->vmcb);
> >> - svm->vmcb_pa = __sme_set(page_to_pfn(page) << PAGE_SHIFT);
> >> + svm->vmcb_pa = __sme_set(page_to_pfn(vmcb01_page) <<
> >> PAGE_SHIFT);
> >> + svm->nested.vmcb01_pa = svm->vmcb_pa;
> >> +
> >> svm->asid_generation = 0;
> >> init_vmcb(svm);
> >>
> >> @@ -1228,13 +1231,13 @@ static int svm_create_vcpu(struct kvm_vcpu
> *vcpu)
> >> return 0;
> >>
> >> free_page4:
> >> - __free_page(hsave_page);
> >> + __free_page(vmcb02_page);
> >> free_page3:
> >> __free_pages(nested_msrpm_pages, MSRPM_ALLOC_ORDER);
> >> free_page2:
> >> __free_pages(msrpm_pages, MSRPM_ALLOC_ORDER);
> >> free_page1:
> >> - __free_page(page);
> >> + __free_page(vmcb01_page);
> >> out:
> >> return err;
> >> }
> >> @@ -1256,11 +1259,11 @@ static void svm_free_vcpu(struct kvm_vcpu
> *vcpu)
> >> * svm_vcpu_load(). So, ensure that no logical CPU has this
> >> * vmcb page recorded as its current vmcb.
> >> */
> >> - svm_clear_current_vmcb(svm->vmcb);
> >>
> >> - __free_page(pfn_to_page(__sme_clr(svm->vmcb_pa) >> PAGE_SHIFT));
> >> + svm_clear_current_vmcb(svm->vmcb);
> >> + __free_page(pfn_to_page(__sme_clr(svm->nested.vmcb01_pa) >>
> >> PAGE_SHIFT));
> >> + __free_page(pfn_to_page(__sme_clr(svm->nested.vmcb02_pa) >>
> >> +PAGE_SHIFT));
> >> __free_pages(virt_to_page(svm->msrpm), MSRPM_ALLOC_ORDER);
> >> - __free_page(virt_to_page(svm->nested.hsave));
> >> __free_pages(virt_to_page(svm->nested.msrpm),
> >> MSRPM_ALLOC_ORDER); }
> >>
> >> @@ -1393,7 +1396,7 @@ static void svm_clear_vintr(struct vcpu_svm *svm)
> >> /* Drop int_ctl fields related to VINTR injection. */
> >> svm->vmcb->control.int_ctl &= mask;
> >> if (is_guest_mode(&svm->vcpu)) {
> >> - svm->nested.hsave->control.int_ctl &= mask;
> >> + svm->vmcb01->control.int_ctl &= mask;
> >>
> >> WARN_ON((svm->vmcb->control.int_ctl & V_TPR_MASK) !=
> >> (svm->nested.ctl.int_ctl & V_TPR_MASK)); @@ -3127,7
> >> +3130,7 @@ bool svm_interrupt_blocked(struct kvm_vcpu *vcpu)
> >> if (is_guest_mode(vcpu)) {
> >> /* As long as interrupts are being delivered... */
> >> if ((svm->nested.ctl.int_ctl & V_INTR_MASKING_MASK)
> >> - ? !(svm->nested.hsave->save.rflags & X86_EFLAGS_IF)
> >> + ? !(svm->vmcb01->save.rflags & X86_EFLAGS_IF)
> >> : !(kvm_get_rflags(vcpu) & X86_EFLAGS_IF))
> >> return true;
> >>
> >> diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index
> >> a798e1731709..e908b83bfa69 100644
> >> --- a/arch/x86/kvm/svm/svm.h
> >> +++ b/arch/x86/kvm/svm/svm.h
> >> @@ -82,7 +82,9 @@ struct kvm_svm {
> >> struct kvm_vcpu;
> >>
> >> struct svm_nested_state {
> >> - struct vmcb *hsave;
> >> + struct vmcb *vmcb02;
> >> + unsigned long vmcb01_pa;
> >> + unsigned long vmcb02_pa;
> >> u64 hsave_msr;
> >> u64 vm_cr_msr;
> >> u64 vmcb;
> >> @@ -102,6 +104,7 @@ struct svm_nested_state { struct vcpu_svm {
> >> struct kvm_vcpu vcpu;
> >> struct vmcb *vmcb;
> >> + struct vmcb *vmcb01;
> >> unsigned long vmcb_pa;
> >> struct svm_cpu_data *svm_data;
> >> uint64_t asid_generation;
> >> @@ -208,10 +211,7 @@ static inline struct vcpu_svm *to_svm(struct
> >> kvm_vcpu
> >> *vcpu)
> >>
> >> static inline struct vmcb *get_host_vmcb(struct vcpu_svm *svm) {
> >> - if (is_guest_mode(&svm->vcpu))
> >> - return svm->nested.hsave;
> >> - else
> >> - return svm->vmcb;
> >> + return svm->vmcb01;
> > Shouldn't it return svm->vmcb? That is what your commit message says.
> I believe this is correct. The function is designed to return the host vmcb which
> will always be vmcb01.
> >
> >> }
> >>
> >> static inline void set_cr_intercept(struct vcpu_svm *svm, int bit)
> >> --
> >> 2.20.1
>

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