From 861377730aa9db4cbaa0f3bd3f4d295c152732c4 Mon Sep 17 00:00:00 2001 From: Tom Lendacky Date: Thu, 10 Dec 2020 11:10:07 -0600 Subject: KVM: SVM: Provide support for SEV-ES vCPU loading An SEV-ES vCPU requires additional VMCB vCPU load/put requirements. SEV-ES hardware will restore certain registers on VMEXIT, but not save them on VMRUN (see Table B-3 and Table B-4 of the AMD64 APM Volume 2), so make the following changes: General vCPU load changes: - During vCPU loading, perform a VMSAVE to the per-CPU SVM save area and save the current values of XCR0, XSS and PKRU to the per-CPU SVM save area as these registers will be restored on VMEXIT. General vCPU put changes: - Do not attempt to restore registers that SEV-ES hardware has already restored on VMEXIT. Signed-off-by: Tom Lendacky Message-Id: <019390e9cb5e93cd73014fa5a040c17d42588733.1607620209.git.thomas.lendacky@amd.com> Signed-off-by: Paolo Bonzini --- arch/x86/include/asm/svm.h | 10 ++++++--- arch/x86/kvm/svm/sev.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++ arch/x86/kvm/svm/svm.c | 36 ++++++++++++++++++++----------- arch/x86/kvm/svm/svm.h | 22 +++++++++++++------ arch/x86/kvm/x86.c | 3 ++- arch/x86/kvm/x86.h | 1 + 6 files changed, 103 insertions(+), 23 deletions(-) diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h index a57331de59e2..1c561945b426 100644 --- a/arch/x86/include/asm/svm.h +++ b/arch/x86/include/asm/svm.h @@ -234,7 +234,8 @@ struct vmcb_save_area { u8 cpl; u8 reserved_2[4]; u64 efer; - u8 reserved_3[112]; + u8 reserved_3[104]; + u64 xss; /* Valid for SEV-ES only */ u64 cr4; u64 cr3; u64 cr0; @@ -265,9 +266,12 @@ struct vmcb_save_area { /* * The following part of the save area is valid only for - * SEV-ES guests when referenced through the GHCB. + * SEV-ES guests when referenced through the GHCB or for + * saving to the host save area. */ - u8 reserved_7[104]; + u8 reserved_7[80]; + u32 pkru; + u8 reserved_7a[20]; u64 reserved_8; /* rax already available at 0x01f8 */ u64 rcx; u64 rdx; diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 584fede0b733..0ddae41e4865 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -16,12 +16,15 @@ #include #include #include +#include #include "x86.h" #include "svm.h" #include "cpuid.h" #include "trace.h" +#define __ex(x) __kvm_handle_fault_on_reboot(x) + static u8 sev_enc_bit; static int sev_flush_asids(void); static DECLARE_RWSEM(sev_deactivate_lock); @@ -1852,3 +1855,54 @@ void sev_es_create_vcpu(struct vcpu_svm *svm) GHCB_VERSION_MIN, sev_enc_bit)); } + +void sev_es_vcpu_load(struct vcpu_svm *svm, int cpu) +{ + struct svm_cpu_data *sd = per_cpu(svm_data, cpu); + struct vmcb_save_area *hostsa; + unsigned int i; + + /* + * As an SEV-ES guest, hardware will restore the host state on VMEXIT, + * of which one step is to perform a VMLOAD. Since hardware does not + * perform a VMSAVE on VMRUN, the host savearea must be updated. + */ + asm volatile(__ex("vmsave") : : "a" (__sme_page_pa(sd->save_area)) : "memory"); + + /* + * Certain MSRs are restored on VMEXIT, only save ones that aren't + * restored. + */ + for (i = 0; i < NR_HOST_SAVE_USER_MSRS; i++) { + if (host_save_user_msrs[i].sev_es_restored) + continue; + + rdmsrl(host_save_user_msrs[i].index, svm->host_user_msrs[i]); + } + + /* XCR0 is restored on VMEXIT, save the current host value */ + hostsa = (struct vmcb_save_area *)(page_address(sd->save_area) + 0x400); + hostsa->xcr0 = xgetbv(XCR_XFEATURE_ENABLED_MASK); + + /* PKRU is restored on VMEXIT, save the curent host value */ + hostsa->pkru = read_pkru(); + + /* MSR_IA32_XSS is restored on VMEXIT, save the currnet host value */ + hostsa->xss = host_xss; +} + +void sev_es_vcpu_put(struct vcpu_svm *svm) +{ + unsigned int i; + + /* + * Certain MSRs are restored on VMEXIT and were saved with vmsave in + * sev_es_vcpu_load() above. Only restore ones that weren't. + */ + for (i = 0; i < NR_HOST_SAVE_USER_MSRS; i++) { + if (host_save_user_msrs[i].sev_es_restored) + continue; + + wrmsrl(host_save_user_msrs[i].index, svm->host_user_msrs[i]); + } +} diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 091f792498a2..3a2e48a8d05c 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -1417,15 +1417,20 @@ static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu) vmcb_mark_all_dirty(svm->vmcb); } + if (sev_es_guest(svm->vcpu.kvm)) { + sev_es_vcpu_load(svm, cpu); + } else { #ifdef CONFIG_X86_64 - rdmsrl(MSR_GS_BASE, to_svm(vcpu)->host.gs_base); + rdmsrl(MSR_GS_BASE, to_svm(vcpu)->host.gs_base); #endif - savesegment(fs, svm->host.fs); - savesegment(gs, svm->host.gs); - svm->host.ldt = kvm_read_ldt(); + savesegment(fs, svm->host.fs); + savesegment(gs, svm->host.gs); + svm->host.ldt = kvm_read_ldt(); - for (i = 0; i < NR_HOST_SAVE_USER_MSRS; i++) - rdmsrl(host_save_user_msrs[i], svm->host_user_msrs[i]); + for (i = 0; i < NR_HOST_SAVE_USER_MSRS; i++) + rdmsrl(host_save_user_msrs[i].index, + svm->host_user_msrs[i]); + } if (static_cpu_has(X86_FEATURE_TSCRATEMSR)) { u64 tsc_ratio = vcpu->arch.tsc_scaling_ratio; @@ -1453,19 +1458,24 @@ static void svm_vcpu_put(struct kvm_vcpu *vcpu) avic_vcpu_put(vcpu); ++vcpu->stat.host_state_reload; - kvm_load_ldt(svm->host.ldt); + if (sev_es_guest(svm->vcpu.kvm)) { + sev_es_vcpu_put(svm); + } else { + kvm_load_ldt(svm->host.ldt); #ifdef CONFIG_X86_64 - loadsegment(fs, svm->host.fs); - wrmsrl(MSR_KERNEL_GS_BASE, current->thread.gsbase); - load_gs_index(svm->host.gs); + loadsegment(fs, svm->host.fs); + wrmsrl(MSR_KERNEL_GS_BASE, current->thread.gsbase); + load_gs_index(svm->host.gs); #else #ifdef CONFIG_X86_32_LAZY_GS - loadsegment(gs, svm->host.gs); + loadsegment(gs, svm->host.gs); #endif #endif - for (i = 0; i < NR_HOST_SAVE_USER_MSRS; i++) - wrmsrl(host_save_user_msrs[i], svm->host_user_msrs[i]); + for (i = 0; i < NR_HOST_SAVE_USER_MSRS; i++) + wrmsrl(host_save_user_msrs[i].index, + svm->host_user_msrs[i]); + } } static unsigned long svm_get_rflags(struct kvm_vcpu *vcpu) diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index 03359185331c..df9fe11a632c 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -23,15 +23,23 @@ #define __sme_page_pa(x) __sme_set(page_to_pfn(x) << PAGE_SHIFT) -static const u32 host_save_user_msrs[] = { +static const struct svm_host_save_msrs { + u32 index; /* Index of the MSR */ + bool sev_es_restored; /* True if MSR is restored on SEV-ES VMEXIT */ +} host_save_user_msrs[] = { #ifdef CONFIG_X86_64 - MSR_STAR, MSR_LSTAR, MSR_CSTAR, MSR_SYSCALL_MASK, MSR_KERNEL_GS_BASE, - MSR_FS_BASE, + { .index = MSR_STAR, .sev_es_restored = true }, + { .index = MSR_LSTAR, .sev_es_restored = true }, + { .index = MSR_CSTAR, .sev_es_restored = true }, + { .index = MSR_SYSCALL_MASK, .sev_es_restored = true }, + { .index = MSR_KERNEL_GS_BASE, .sev_es_restored = true }, + { .index = MSR_FS_BASE, .sev_es_restored = true }, #endif - MSR_IA32_SYSENTER_CS, MSR_IA32_SYSENTER_ESP, MSR_IA32_SYSENTER_EIP, - MSR_TSC_AUX, + { .index = MSR_IA32_SYSENTER_CS, .sev_es_restored = true }, + { .index = MSR_IA32_SYSENTER_ESP, .sev_es_restored = true }, + { .index = MSR_IA32_SYSENTER_EIP, .sev_es_restored = true }, + { .index = MSR_TSC_AUX, .sev_es_restored = false }, }; - #define NR_HOST_SAVE_USER_MSRS ARRAY_SIZE(host_save_user_msrs) #define MAX_DIRECT_ACCESS_MSRS 18 @@ -580,5 +588,7 @@ int sev_handle_vmgexit(struct vcpu_svm *svm); int sev_es_string_io(struct vcpu_svm *svm, int size, unsigned int port, int in); void sev_es_init_vmcb(struct vcpu_svm *svm); void sev_es_create_vcpu(struct vcpu_svm *svm); +void sev_es_vcpu_load(struct vcpu_svm *svm, int cpu); +void sev_es_vcpu_put(struct vcpu_svm *svm); #endif diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index eea0e9fed62a..3e58612babfe 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -197,7 +197,8 @@ EXPORT_SYMBOL_GPL(host_efer); bool __read_mostly allow_smaller_maxphyaddr = 0; EXPORT_SYMBOL_GPL(allow_smaller_maxphyaddr); -static u64 __read_mostly host_xss; +u64 __read_mostly host_xss; +EXPORT_SYMBOL_GPL(host_xss); u64 __read_mostly supported_xss; EXPORT_SYMBOL_GPL(supported_xss); diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h index fe7f3df91b2c..c5ee0f5ce0f1 100644 --- a/arch/x86/kvm/x86.h +++ b/arch/x86/kvm/x86.h @@ -279,6 +279,7 @@ fastpath_t handle_fastpath_set_msr_irqoff(struct kvm_vcpu *vcpu); extern u64 host_xcr0; extern u64 supported_xcr0; +extern u64 host_xss; extern u64 supported_xss; static inline bool kvm_mpx_supported(void) -- cgit v1.2.3