From 2b036c6b861dc5da295c6fe19a3edcff7093fdeb Mon Sep 17 00:00:00 2001 From: Boris Ostrovsky Date: Mon, 9 Jan 2012 14:00:35 -0500 Subject: KVM: SVM: Add support for AMD's OSVW feature in guests In some cases guests should not provide workarounds for errata even when the physical processor is affected. For example, because of erratum 400 on family 10h processors a Linux guest will read an MSR (resulting in VMEXIT) before going to idle in order to avoid getting stuck in a non-C0 state. This is not necessary: HLT and IO instructions are intercepted and therefore there is no reason for erratum 400 workaround in the guest. This patch allows us to present a guest with certain errata as fixed, regardless of the state of actual hardware. Signed-off-by: Boris Ostrovsky Signed-off-by: Marcelo Tosatti Signed-off-by: Avi Kivity --- arch/x86/kvm/svm.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 59 insertions(+) (limited to 'arch/x86/kvm/svm.c') diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 5fa553babe56..fce3ba0f2079 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -110,6 +110,12 @@ struct nested_state { #define MSRPM_OFFSETS 16 static u32 msrpm_offsets[MSRPM_OFFSETS] __read_mostly; +/* + * Set osvw_len to higher value when updated Revision Guides + * are published and we know what the new status bits are + */ +static uint64_t osvw_len = 4, osvw_status; + struct vcpu_svm { struct kvm_vcpu vcpu; struct vmcb *vmcb; @@ -556,6 +562,27 @@ static void svm_init_erratum_383(void) erratum_383_found = true; } +static void svm_init_osvw(struct kvm_vcpu *vcpu) +{ + /* + * Guests should see errata 400 and 415 as fixed (assuming that + * HLT and IO instructions are intercepted). + */ + vcpu->arch.osvw.length = (osvw_len >= 3) ? (osvw_len) : 3; + vcpu->arch.osvw.status = osvw_status & ~(6ULL); + + /* + * By increasing VCPU's osvw.length to 3 we are telling the guest that + * all osvw.status bits inside that length, including bit 0 (which is + * reserved for erratum 298), are valid. However, if host processor's + * osvw_len is 0 then osvw_status[0] carries no information. We need to + * be conservative here and therefore we tell the guest that erratum 298 + * is present (because we really don't know). + */ + if (osvw_len == 0 && boot_cpu_data.x86 == 0x10) + vcpu->arch.osvw.status |= 1; +} + static int has_svm(void) { const char *msg; @@ -620,6 +647,36 @@ static int svm_hardware_enable(void *garbage) __get_cpu_var(current_tsc_ratio) = TSC_RATIO_DEFAULT; } + + /* + * Get OSVW bits. + * + * Note that it is possible to have a system with mixed processor + * revisions and therefore different OSVW bits. If bits are not the same + * on different processors then choose the worst case (i.e. if erratum + * is present on one processor and not on another then assume that the + * erratum is present everywhere). + */ + if (cpu_has(&boot_cpu_data, X86_FEATURE_OSVW)) { + uint64_t len, status = 0; + int err; + + len = native_read_msr_safe(MSR_AMD64_OSVW_ID_LENGTH, &err); + if (!err) + status = native_read_msr_safe(MSR_AMD64_OSVW_STATUS, + &err); + + if (err) + osvw_status = osvw_len = 0; + else { + if (len < osvw_len) + osvw_len = len; + osvw_status |= status; + osvw_status &= (1ULL << osvw_len) - 1; + } + } else + osvw_status = osvw_len = 0; + svm_init_erratum_383(); return 0; @@ -1186,6 +1243,8 @@ static struct kvm_vcpu *svm_create_vcpu(struct kvm *kvm, unsigned int id) if (kvm_vcpu_is_bsp(&svm->vcpu)) svm->vcpu.arch.apic_base |= MSR_IA32_APICBASE_BSP; + svm_init_osvw(&svm->vcpu); + return &svm->vcpu; free_page4: -- cgit v1.2.2 From e2358851efbcdc34583ee11971a6e4d587ea8bf9 Mon Sep 17 00:00:00 2001 From: Davidlohr Bueso Date: Tue, 17 Jan 2012 14:09:50 +0100 Subject: KVM: SVM: comment nested paging and virtualization module parameters Also use true instead of 1 for enabling by default. Signed-off-by: Davidlohr Bueso Signed-off-by: Marcelo Tosatti Signed-off-by: Avi Kivity --- arch/x86/kvm/svm.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'arch/x86/kvm/svm.c') diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index fce3ba0f2079..7bbd17cc3488 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -182,11 +182,13 @@ static bool npt_enabled = true; #else static bool npt_enabled; #endif -static int npt = 1; +/* allow nested paging (virtualized MMU) for all guests */ +static int npt = true; module_param(npt, int, S_IRUGO); -static int nested = 1; +/* allow nested virtualization in KVM/SVM */ +static int nested = true; module_param(nested, int, S_IRUGO); static void svm_flush_tlb(struct kvm_vcpu *vcpu); -- cgit v1.2.2 From cc578287e3224d0da196cc1d226bdae6b068faa7 Mon Sep 17 00:00:00 2001 From: Zachary Amsden Date: Fri, 3 Feb 2012 15:43:50 -0200 Subject: KVM: Infrastructure for software and hardware based TSC rate scaling This requires some restructuring; rather than use 'virtual_tsc_khz' to indicate whether hardware rate scaling is in effect, we consider each VCPU to always have a virtual TSC rate. Instead, there is new logic above the vendor-specific hardware scaling that decides whether it is even necessary to use and updates all rate variables used by common code. This means we can simply query the virtual rate at any point, which is needed for software rate scaling. There is also now a threshold added to the TSC rate scaling; minor differences and variations of measured TSC rate can accidentally provoke rate scaling to be used when it is not needed. Instead, we have a tolerance variable called tsc_tolerance_ppm, which is the maximum variation from user requested rate at which scaling will be used. The default is 250ppm, which is the half the threshold for NTP adjustment, allowing for some hardware variation. In the event that hardware rate scaling is not available, we can kludge a bit by forcing TSC catchup to turn on when a faster than hardware speed has been requested, but there is nothing available yet for the reverse case; this requires a trap and emulate software implementation for RDTSC, which is still forthcoming. [avi: fix 64-bit division on i386] Signed-off-by: Zachary Amsden Signed-off-by: Marcelo Tosatti Signed-off-by: Avi Kivity --- arch/x86/kvm/svm.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) (limited to 'arch/x86/kvm/svm.c') diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 7bbd17cc3488..e12026e5244e 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -964,20 +964,25 @@ static u64 svm_scale_tsc(struct kvm_vcpu *vcpu, u64 tsc) return _tsc; } -static void svm_set_tsc_khz(struct kvm_vcpu *vcpu, u32 user_tsc_khz) +static void svm_set_tsc_khz(struct kvm_vcpu *vcpu, u32 user_tsc_khz, bool scale) { struct vcpu_svm *svm = to_svm(vcpu); u64 ratio; u64 khz; - /* TSC scaling supported? */ - if (!boot_cpu_has(X86_FEATURE_TSCRATEMSR)) + /* Guest TSC same frequency as host TSC? */ + if (!scale) { + svm->tsc_ratio = TSC_RATIO_DEFAULT; return; + } - /* TSC-Scaling disabled or guest TSC same frequency as host TSC? */ - if (user_tsc_khz == 0) { - vcpu->arch.virtual_tsc_khz = 0; - svm->tsc_ratio = TSC_RATIO_DEFAULT; + /* TSC scaling supported? */ + if (!boot_cpu_has(X86_FEATURE_TSCRATEMSR)) { + if (user_tsc_khz > tsc_khz) { + vcpu->arch.tsc_catchup = 1; + vcpu->arch.tsc_always_catchup = 1; + } else + WARN(1, "user requested TSC rate below hardware speed\n"); return; } @@ -992,7 +997,6 @@ static void svm_set_tsc_khz(struct kvm_vcpu *vcpu, u32 user_tsc_khz) user_tsc_khz); return; } - vcpu->arch.virtual_tsc_khz = user_tsc_khz; svm->tsc_ratio = ratio; } -- cgit v1.2.2 From f1e2b26003c41e581243c09ceed7567677449468 Mon Sep 17 00:00:00 2001 From: Marcelo Tosatti Date: Fri, 3 Feb 2012 15:43:55 -0200 Subject: KVM: Allow adjust_tsc_offset to be in host or guest cycles Redefine the API to take a parameter indicating whether an adjustment is in host or guest cycles. Signed-off-by: Zachary Amsden Signed-off-by: Marcelo Tosatti Signed-off-by: Avi Kivity --- arch/x86/kvm/svm.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'arch/x86/kvm/svm.c') diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index e12026e5244e..0b7690ee20bd 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -1016,10 +1016,14 @@ static void svm_write_tsc_offset(struct kvm_vcpu *vcpu, u64 offset) mark_dirty(svm->vmcb, VMCB_INTERCEPTS); } -static void svm_adjust_tsc_offset(struct kvm_vcpu *vcpu, s64 adjustment) +static void svm_adjust_tsc_offset(struct kvm_vcpu *vcpu, s64 adjustment, bool host) { struct vcpu_svm *svm = to_svm(vcpu); + WARN_ON(adjustment < 0); + if (host) + adjustment = svm_scale_tsc(vcpu, adjustment); + svm->vmcb->control.tsc_offset += adjustment; if (is_guest_mode(vcpu)) svm->nested.hsave->control.tsc_offset += adjustment; -- cgit v1.2.2 From 7f3d35fddd173e52886d03bc34b5b5d6f5bea343 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Wed, 8 Feb 2012 14:34:38 +0100 Subject: KVM: x86 emulator: Fix task switch privilege checks Currently, all task switches check privileges against the DPL of the TSS. This is only correct for jmp/call to a TSS. If a task gate is used, the DPL of this take gate is used for the check instead. Exceptions, external interrupts and iret shouldn't perform any check. [avi: kill kvm-kmod remnants] Signed-off-by: Kevin Wolf Signed-off-by: Avi Kivity --- arch/x86/kvm/svm.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'arch/x86/kvm/svm.c') diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 0b7690ee20bd..95cdeaf9c718 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -2799,7 +2799,10 @@ static int task_switch_interception(struct vcpu_svm *svm) (int_vec == OF_VECTOR || int_vec == BP_VECTOR))) skip_emulated_instruction(&svm->vcpu); - if (kvm_task_switch(&svm->vcpu, tss_selector, reason, + if (int_type != SVM_EXITINTINFO_TYPE_SOFT) + int_vec = -1; + + if (kvm_task_switch(&svm->vcpu, tss_selector, int_vec, reason, has_error_code, error_code) == EMULATE_FAIL) { svm->vcpu.run->exit_reason = KVM_EXIT_INTERNAL_ERROR; svm->vcpu.run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION; -- cgit v1.2.2 From ea5e97e8bf1d56a4d9461c39e082b9c31a7be4ff Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Wed, 8 Feb 2012 14:34:40 +0100 Subject: KVM: SVM: Fix CPL updates Keep CPL at 0 in real mode and at 3 in VM86. In protected/long mode, use RPL rather than DPL of the code segment. Signed-off-by: Kevin Wolf Signed-off-by: Avi Kivity --- arch/x86/kvm/svm.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) (limited to 'arch/x86/kvm/svm.c') diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 95cdeaf9c718..ab39d84dee00 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -1332,6 +1332,21 @@ static void svm_vcpu_put(struct kvm_vcpu *vcpu) wrmsrl(host_save_user_msrs[i], svm->host_user_msrs[i]); } +static void svm_update_cpl(struct kvm_vcpu *vcpu) +{ + struct vcpu_svm *svm = to_svm(vcpu); + int cpl; + + if (!is_protmode(vcpu)) + cpl = 0; + else if (svm->vmcb->save.rflags & X86_EFLAGS_VM) + cpl = 3; + else + cpl = svm->vmcb->save.cs.selector & 0x3; + + svm->vmcb->save.cpl = cpl; +} + static unsigned long svm_get_rflags(struct kvm_vcpu *vcpu) { return to_svm(vcpu)->vmcb->save.rflags; @@ -1607,9 +1622,7 @@ static void svm_set_segment(struct kvm_vcpu *vcpu, s->attrib |= (var->g & 1) << SVM_SELECTOR_G_SHIFT; } if (seg == VCPU_SREG_CS) - svm->vmcb->save.cpl - = (svm->vmcb->save.cs.attrib - >> SVM_SELECTOR_DPL_SHIFT) & 3; + svm_update_cpl(vcpu); mark_dirty(svm->vmcb, VMCB_SEG); } -- cgit v1.2.2 From 4cee4798a304ee1ea579423ca048f16ceaccdfb5 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Wed, 8 Feb 2012 14:34:41 +0100 Subject: KVM: x86 emulator: Allow PM/VM86 switch during task switch Task switches can switch between Protected Mode and VM86. The current mode must be updated during the task switch emulation so that the new segment selectors are interpreted correctly. In order to let privilege checks succeed, rflags needs to be updated in the vcpu struct as this causes a CPL update. Signed-off-by: Kevin Wolf Signed-off-by: Avi Kivity --- arch/x86/kvm/svm.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'arch/x86/kvm/svm.c') diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index ab39d84dee00..53efd597f39e 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -1354,7 +1354,11 @@ static unsigned long svm_get_rflags(struct kvm_vcpu *vcpu) static void svm_set_rflags(struct kvm_vcpu *vcpu, unsigned long rflags) { + unsigned long old_rflags = to_svm(vcpu)->vmcb->save.rflags; + to_svm(vcpu)->vmcb->save.rflags = rflags; + if ((old_rflags ^ rflags) & X86_EFLAGS_VM) + svm_update_cpl(vcpu); } static void svm_cache_reg(struct kvm_vcpu *vcpu, enum kvm_reg reg) -- cgit v1.2.2