From 61d2ef2ce3e0161bedf5d2867f546a8df77fa9bc Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Wed, 28 Apr 2010 16:40:38 +0300 Subject: [PATCH] KVM: VMX: Add facility to atomically switch MSRs on guest entry/exit Some guest msr values cannot be used on the host (for example. EFER.NX=0), so we need to switch them atomically during guest entry or exit. Add a facility to program the vmx msr autoload registers accordingly. Signed-off-by: Avi Kivity --- arch/x86/kvm/vmx.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 49 insertions(+) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 2e8729678600..ae22dcf17211 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -98,6 +98,8 @@ module_param(ple_gap, int, S_IRUGO); static int ple_window = KVM_VMX_DEFAULT_PLE_WINDOW; module_param(ple_window, int, S_IRUGO); +#define NR_AUTOLOAD_MSRS 1 + struct vmcs { u32 revision_id; u32 abort; @@ -125,6 +127,11 @@ struct vcpu_vmx { u64 msr_guest_kernel_gs_base; #endif struct vmcs *vmcs; + struct msr_autoload { + unsigned nr; + struct vmx_msr_entry guest[NR_AUTOLOAD_MSRS]; + struct vmx_msr_entry host[NR_AUTOLOAD_MSRS]; + } msr_autoload; struct { int loaded; u16 fs_sel, gs_sel, ldt_sel; @@ -595,6 +602,46 @@ static void update_exception_bitmap(struct kvm_vcpu *vcpu) vmcs_write32(EXCEPTION_BITMAP, eb); } +static void clear_atomic_switch_msr(struct vcpu_vmx *vmx, unsigned msr) +{ + unsigned i; + struct msr_autoload *m = &vmx->msr_autoload; + + for (i = 0; i < m->nr; ++i) + if (m->guest[i].index == msr) + break; + + if (i == m->nr) + return; + --m->nr; + m->guest[i] = m->guest[m->nr]; + m->host[i] = m->host[m->nr]; + vmcs_write32(VM_ENTRY_MSR_LOAD_COUNT, m->nr); + vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, m->nr); +} + +static void add_atomic_switch_msr(struct vcpu_vmx *vmx, unsigned msr, + u64 guest_val, u64 host_val) +{ + unsigned i; + struct msr_autoload *m = &vmx->msr_autoload; + + for (i = 0; i < m->nr; ++i) + if (m->guest[i].index == msr) + break; + + if (i == m->nr) { + ++m->nr; + vmcs_write32(VM_ENTRY_MSR_LOAD_COUNT, m->nr); + vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, m->nr); + } + + m->guest[i].index = msr; + m->guest[i].value = guest_val; + m->host[i].index = msr; + m->host[i].value = host_val; +} + static void reload_tss(void) { /* @@ -2470,7 +2517,9 @@ static int vmx_vcpu_setup(struct vcpu_vmx *vmx) vmcs_writel(HOST_RIP, kvm_vmx_return); /* 22.2.5 */ vmcs_write32(VM_EXIT_MSR_STORE_COUNT, 0); vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, 0); + vmcs_write64(VM_EXIT_MSR_LOAD_ADDR, __pa(vmx->msr_autoload.host)); vmcs_write32(VM_ENTRY_MSR_LOAD_COUNT, 0); + vmcs_write64(VM_ENTRY_MSR_LOAD_ADDR, __pa(vmx->msr_autoload.guest)); rdmsr(MSR_IA32_SYSENTER_CS, host_sysenter_cs, junk); vmcs_write32(HOST_IA32_SYSENTER_CS, host_sysenter_cs); -- 2.20.1