From: Dexuan Cui <dexuan.cui@xxxxxxxxx> Enable XSAVE/XRSTORE for guest. Change from V2: Addressed comments from Avi. Change from V1: 1. Use FPU API. 2. Fix CPUID issue. 3. Save/restore all possible guest xstate fields when switching. Because we don't know which fields guest has already touched. Signed-off-by: Dexuan Cui <dexuan.cui@xxxxxxxxx> Signed-off-by: Sheng Yang <sheng@xxxxxxxxxxxxxxx> --- Avi, could you help to review this kernel patch first? Testcase and LM are in progress now. arch/x86/include/asm/kvm_host.h | 1 + arch/x86/include/asm/vmx.h | 1 + arch/x86/kvm/vmx.c | 28 ++++++++++++ arch/x86/kvm/x86.c | 88 +++++++++++++++++++++++++++++++++++--- 4 files changed, 111 insertions(+), 7 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index d08bb4a..3938bd1 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -302,6 +302,7 @@ struct kvm_vcpu_arch { } update_pte; struct fpu guest_fpu; + u64 xcr0; gva_t mmio_fault_cr2; struct kvm_pio_request pio; diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h index 9e6779f..346ea66 100644 --- a/arch/x86/include/asm/vmx.h +++ b/arch/x86/include/asm/vmx.h @@ -266,6 +266,7 @@ enum vmcs_field { #define EXIT_REASON_EPT_VIOLATION 48 #define EXIT_REASON_EPT_MISCONFIG 49 #define EXIT_REASON_WBINVD 54 +#define EXIT_REASON_XSETBV 55 /* * Interruption-information format diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 99ae513..a63f206 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -36,6 +36,8 @@ #include <asm/vmx.h> #include <asm/virtext.h> #include <asm/mce.h> +#include <asm/i387.h> +#include <asm/xcr.h> #include "trace.h" @@ -247,6 +249,9 @@ static const u32 vmx_msr_index[] = { }; #define NR_VMX_MSR ARRAY_SIZE(vmx_msr_index) +#define MERGE_TO_U64(low, high) \ + (((low) & -1u) | ((u64)((high) & -1u) << 32)) + static inline bool is_page_fault(u32 intr_info) { return (intr_info & (INTR_INFO_INTR_TYPE_MASK | INTR_INFO_VECTOR_MASK | @@ -3354,6 +3359,28 @@ static int handle_wbinvd(struct kvm_vcpu *vcpu) return 1; } +static int handle_xsetbv(struct kvm_vcpu *vcpu) +{ + u64 new_bv = MERGE_TO_U64(kvm_register_read(vcpu, VCPU_REGS_RAX), + kvm_register_read(vcpu, VCPU_REGS_RDX)); + + if (kvm_register_read(vcpu, VCPU_REGS_RCX) != 0) + goto err; + if (vmx_get_cpl(vcpu) != 0) + goto err; + if (!(new_bv & XSTATE_FP)) + goto err; + if ((new_bv & XSTATE_YMM) && !(new_bv & XSTATE_SSE)) + goto err; + vcpu->arch.xcr0 = new_bv; + xsetbv(XCR_XFEATURE_ENABLED_MASK, vcpu->arch.xcr0); + skip_emulated_instruction(vcpu); + return 1; +err: + kvm_inject_gp(vcpu, 0); + return 1; +} + static int handle_apic_access(struct kvm_vcpu *vcpu) { return emulate_instruction(vcpu, 0, 0, 0) == EMULATE_DONE; @@ -3632,6 +3659,7 @@ static int (*kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = { [EXIT_REASON_TPR_BELOW_THRESHOLD] = handle_tpr_below_threshold, [EXIT_REASON_APIC_ACCESS] = handle_apic_access, [EXIT_REASON_WBINVD] = handle_wbinvd, + [EXIT_REASON_XSETBV] = handle_xsetbv, [EXIT_REASON_TASK_SWITCH] = handle_task_switch, [EXIT_REASON_MCE_DURING_VMENTRY] = handle_machine_check, [EXIT_REASON_EPT_VIOLATION] = handle_ept_violation, diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 7be1d36..7580d14 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -64,6 +64,7 @@ (~(unsigned long)(X86_CR4_VME | X86_CR4_PVI | X86_CR4_TSD | X86_CR4_DE\ | X86_CR4_PSE | X86_CR4_PAE | X86_CR4_MCE \ | X86_CR4_PGE | X86_CR4_PCE | X86_CR4_OSFXSR \ + | X86_CR4_OSXSAVE \ | X86_CR4_OSXMMEXCPT | X86_CR4_VMXE)) #define CR8_RESERVED_BITS (~(unsigned long)X86_CR8_TPR) @@ -149,6 +150,13 @@ struct kvm_stats_debugfs_item debugfs_entries[] = { { NULL } }; +static u64 host_xcr0; + +static inline u32 bit(int bitno) +{ + return 1 << (bitno & 31); +} + static void kvm_on_user_return(struct user_return_notifier *urn) { unsigned slot; @@ -473,6 +481,30 @@ void kvm_lmsw(struct kvm_vcpu *vcpu, unsigned long msw) } EXPORT_SYMBOL_GPL(kvm_lmsw); +static bool guest_cpuid_has_xsave(struct kvm_vcpu *vcpu) +{ + struct kvm_cpuid_entry2 *best; + + best = kvm_find_cpuid_entry(vcpu, 1, 0); + return best && (best->ecx & bit(X86_FEATURE_XSAVE)); +} + +static void update_cpuid(struct kvm_vcpu *vcpu) +{ + struct kvm_cpuid_entry2 *best; + + best = kvm_find_cpuid_entry(vcpu, 1, 0); + if (!best) + return; + + /* Update OSXSAVE bit */ + if (cpu_has_xsave && best->function == 0x1) { + best->ecx &= ~(bit(X86_FEATURE_OSXSAVE)); + if (kvm_read_cr4(vcpu) & X86_CR4_OSXSAVE) + best->ecx |= bit(X86_FEATURE_OSXSAVE); + } +} + int __kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) { unsigned long old_cr4 = kvm_read_cr4(vcpu); @@ -481,6 +513,9 @@ int __kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) if (cr4 & CR4_RESERVED_BITS) return 1; + if (!guest_cpuid_has_xsave(vcpu) && (cr4 & X86_CR4_OSXSAVE)) + return 1; + if (is_long_mode(vcpu)) { if (!(cr4 & X86_CR4_PAE)) return 1; @@ -497,6 +532,9 @@ int __kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) if ((cr4 ^ old_cr4) & pdptr_bits) kvm_mmu_reset_context(vcpu); + if ((cr4 ^ old_cr4) & X86_CR4_OSXSAVE) + update_cpuid(vcpu); + return 0; } @@ -665,11 +703,6 @@ int kvm_get_dr(struct kvm_vcpu *vcpu, int dr, unsigned long *val) } EXPORT_SYMBOL_GPL(kvm_get_dr); -static inline u32 bit(int bitno) -{ - return 1 << (bitno & 31); -} - /* * List of msr numbers which we expose to userspace through KVM_GET_MSRS * and KVM_SET_MSRS, and KVM_GET_MSR_INDEX_LIST. @@ -1916,7 +1949,7 @@ static void do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function, 0 /* Reserved */ | F(CX16) | 0 /* xTPR Update, PDCM */ | 0 /* Reserved, DCA */ | F(XMM4_1) | F(XMM4_2) | F(X2APIC) | F(MOVBE) | F(POPCNT) | - 0 /* Reserved, XSAVE, OSXSAVE */; + 0 /* Reserved, AES */ | F(XSAVE) | 0 /* OSXSAVE */; /* cpuid 0x80000001.ecx */ const u32 kvm_supported_word6_x86_features = F(LAHF_LM) | F(CMP_LEGACY) | F(SVM) | 0 /* ExtApicSpace */ | @@ -1931,7 +1964,7 @@ static void do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function, switch (function) { case 0: - entry->eax = min(entry->eax, (u32)0xb); + entry->eax = min(entry->eax, (u32)0xd); break; case 1: entry->edx &= kvm_supported_word0_x86_features; @@ -1989,6 +2022,20 @@ static void do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function, } break; } + case 0xd: { + int i; + + entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX; + for (i = 1; *nent < maxnent; ++i) { + if (entry[i - 1].eax == 0 && i != 2) + break; + do_cpuid_1_ent(&entry[i], function, i); + entry[i].flags |= + KVM_CPUID_FLAG_SIGNIFCANT_INDEX; + ++*nent; + } + break; + } case KVM_CPUID_SIGNATURE: { char signature[12] = "KVMKVMKVM\0\0"; u32 *sigptr = (u32 *)signature; @@ -4124,6 +4171,8 @@ int kvm_arch_init(void *opaque) perf_register_guest_info_callbacks(&kvm_guest_cbs); + host_xcr0 = xgetbv(XCR_XFEATURE_ENABLED_MASK); + return 0; out: @@ -4567,6 +4616,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) kvm_x86_ops->prepare_guest_switch(vcpu); if (vcpu->fpu_active) kvm_load_guest_fpu(vcpu); + if (kvm_read_cr4(vcpu) & X86_CR4_OSXSAVE) + xsetbv(XCR_XFEATURE_ENABLED_MASK, vcpu->arch.xcr0); atomic_set(&vcpu->guest_mode, 1); smp_wmb(); @@ -5118,6 +5169,10 @@ void fx_init(struct kvm_vcpu *vcpu) fpu_alloc(&vcpu->arch.guest_fpu); fpu_finit(&vcpu->arch.guest_fpu); + /* Ensure guest xcr0 is valid for loading */ + if (cpu_has_xsave) + vcpu->arch.xcr0 = XSTATE_FP; + vcpu->arch.cr0 |= X86_CR0_ET; } EXPORT_SYMBOL_GPL(fx_init); @@ -5127,6 +5182,14 @@ static void fx_free(struct kvm_vcpu *vcpu) fpu_free(&vcpu->arch.guest_fpu); } +static u64 cpuid_get_possible_xcr0(struct kvm_vcpu *vcpu) +{ + unsigned int eax, ebx, ecx, edx; + + cpuid_count(0xd, 0, &eax, &ebx, &ecx, &edx); + return eax + ((u64)edx << 32); +} + void kvm_load_guest_fpu(struct kvm_vcpu *vcpu) { if (vcpu->guest_fpu_loaded) @@ -5134,6 +5197,10 @@ void kvm_load_guest_fpu(struct kvm_vcpu *vcpu) vcpu->guest_fpu_loaded = 1; unlazy_fpu(current); + /* Restore all possible states in the guest */ + if (cpu_has_xsave && guest_cpuid_has_xsave(vcpu)) + xsetbv(XCR_XFEATURE_ENABLED_MASK, + cpuid_get_possible_xcr0(vcpu)); fpu_restore_checking(&vcpu->arch.guest_fpu); trace_kvm_fpu(1); } @@ -5144,7 +5211,14 @@ void kvm_put_guest_fpu(struct kvm_vcpu *vcpu) return; vcpu->guest_fpu_loaded = 0; + /* Save all possible states in the guest */ + if (cpu_has_xsave && guest_cpuid_has_xsave(vcpu)) + xsetbv(XCR_XFEATURE_ENABLED_MASK, + cpuid_get_possible_xcr0(vcpu)); fpu_save_init(&vcpu->arch.guest_fpu); + if (cpu_has_xsave) + xsetbv(XCR_XFEATURE_ENABLED_MASK, + host_xcr0); ++vcpu->stat.fpu_reload; set_bit(KVM_REQ_DEACTIVATE_FPU, &vcpu->requests); trace_kvm_fpu(0); -- 1.7.0.1 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html