From 312a1c87798e6b43ff533393167b3cba33645ead Mon Sep 17 00:00:00 2001 From: Aaron Lewis Date: Mon, 21 Oct 2019 16:30:23 -0700 Subject: [PATCH] KVM: SVM: Use wrmsr for switching between guest and host IA32_XSS on AMD When the guest can execute the XSAVES/XRSTORS instructions, set the hardware IA32_XSS MSR to guest/host values on VM-entry/VM-exit. Note that vcpu->arch.ia32_xss is currently guaranteed to be 0 on AMD, since there is no way to change it. Suggested-by: Sean Christopherson Reviewed-by: Jim Mattson Signed-off-by: Aaron Lewis Change-Id: Id51a782462086e6d7a3ab621838e200f1c005afd Signed-off-by: Paolo Bonzini --- arch/x86/kvm/svm.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index cf224963e7d1..fa29125193fe 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -116,6 +116,8 @@ MODULE_DEVICE_TABLE(x86cpu, svm_cpu_id); static bool erratum_383_found __read_mostly; +static u64 __read_mostly host_xss; + static const u32 host_save_user_msrs[] = { #ifdef CONFIG_X86_64 MSR_STAR, MSR_LSTAR, MSR_CSTAR, MSR_SYSCALL_MASK, MSR_KERNEL_GS_BASE, @@ -1409,6 +1411,9 @@ static __init int svm_hardware_setup(void) pr_info("Virtual GIF supported\n"); } + if (boot_cpu_has(X86_FEATURE_XSAVES)) + rdmsrl(MSR_IA32_XSS, host_xss); + return 0; err: @@ -5598,6 +5603,22 @@ static void svm_cancel_injection(struct kvm_vcpu *vcpu) svm_complete_interrupts(svm); } +static void svm_load_guest_xss(struct kvm_vcpu *vcpu) +{ + if (kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE) && + vcpu->arch.xsaves_enabled && + vcpu->arch.ia32_xss != host_xss) + wrmsrl(MSR_IA32_XSS, vcpu->arch.ia32_xss); +} + +static void svm_load_host_xss(struct kvm_vcpu *vcpu) +{ + if (kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE) && + vcpu->arch.xsaves_enabled && + vcpu->arch.ia32_xss != host_xss) + wrmsrl(MSR_IA32_XSS, host_xss); +} + static void svm_vcpu_run(struct kvm_vcpu *vcpu) { struct vcpu_svm *svm = to_svm(vcpu); @@ -5637,6 +5658,7 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu) clgi(); kvm_load_guest_xcr0(vcpu); + svm_load_guest_xss(vcpu); if (lapic_in_kernel(vcpu) && vcpu->arch.apic->lapic_timer.timer_advance_ns) @@ -5786,6 +5808,7 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu) if (unlikely(svm->vmcb->control.exit_code == SVM_EXIT_NMI)) kvm_before_interrupt(&svm->vcpu); + svm_load_host_xss(vcpu); kvm_put_guest_xcr0(vcpu); stgi();