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Subject[RFC PATCH v2 23/33] KVM: x86: Update __get_sregs() / __set_sregs() to support SEV-ES
Date
From: Tom Lendacky <thomas.lendacky@amd.com>

Since many of the registers used by the SEV-ES are encrypted and cannot
be read or written, adjust the __get_sregs() / __set_sregs() to take into
account whether the VMSA/guest state is encrypted.

For __get_sregs(), return the actual value that is in use by the guest
for all registers being tracked using the write trap support.

For __set_sregs(), skip setting of all guest registers values.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
---
arch/x86/kvm/x86.c | 27 ++++++++++++++++++---------
1 file changed, 18 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 90a551360207..39c8d9a311d4 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9320,6 +9320,9 @@ static void __get_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs)
{
struct desc_ptr dt;

+ if (vcpu->arch.guest_state_protected)
+ goto skip_protected_regs;
+
kvm_get_segment(vcpu, &sregs->cs, VCPU_SREG_CS);
kvm_get_segment(vcpu, &sregs->ds, VCPU_SREG_DS);
kvm_get_segment(vcpu, &sregs->es, VCPU_SREG_ES);
@@ -9337,9 +9340,11 @@ static void __get_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs)
sregs->gdt.limit = dt.size;
sregs->gdt.base = dt.address;

- sregs->cr0 = kvm_read_cr0(vcpu);
sregs->cr2 = vcpu->arch.cr2;
sregs->cr3 = kvm_read_cr3(vcpu);
+
+skip_protected_regs:
+ sregs->cr0 = kvm_read_cr0(vcpu);
sregs->cr4 = kvm_read_cr4(vcpu);
sregs->cr8 = kvm_get_cr8(vcpu);
sregs->efer = vcpu->arch.efer;
@@ -9478,6 +9483,9 @@ static int __set_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs)
if (kvm_set_apic_base(vcpu, &apic_base_msr))
goto out;

+ if (vcpu->arch.guest_state_protected)
+ goto skip_protected_regs;
+
dt.size = sregs->idt.limit;
dt.address = sregs->idt.base;
kvm_x86_ops.set_idt(vcpu, &dt);
@@ -9516,14 +9524,6 @@ static int __set_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs)
if (mmu_reset_needed)
kvm_mmu_reset_context(vcpu);

- max_bits = KVM_NR_INTERRUPTS;
- pending_vec = find_first_bit(
- (const unsigned long *)sregs->interrupt_bitmap, max_bits);
- if (pending_vec < max_bits) {
- kvm_queue_interrupt(vcpu, pending_vec, false);
- pr_debug("Set back pending irq %d\n", pending_vec);
- }
-
kvm_set_segment(vcpu, &sregs->cs, VCPU_SREG_CS);
kvm_set_segment(vcpu, &sregs->ds, VCPU_SREG_DS);
kvm_set_segment(vcpu, &sregs->es, VCPU_SREG_ES);
@@ -9542,6 +9542,15 @@ static int __set_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs)
!is_protmode(vcpu))
vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;

+skip_protected_regs:
+ max_bits = KVM_NR_INTERRUPTS;
+ pending_vec = find_first_bit(
+ (const unsigned long *)sregs->interrupt_bitmap, max_bits);
+ if (pending_vec < max_bits) {
+ kvm_queue_interrupt(vcpu, pending_vec, false);
+ pr_debug("Set back pending irq %d\n", pending_vec);
+ }
+
kvm_make_request(KVM_REQ_EVENT, vcpu);

ret = 0;
--
2.28.0
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