[RFC PATCH v2 23/33] KVM: x86: Update __get_sregs() / __set_sregs() to support SEV-ES

[Tom Lendacky <thomas.lendacky@amd.com>]

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