From 127770ac0d043435375ab86434f31a93efa88215 Mon Sep 17 00:00:00 2001 From: Aaron Lewis Date: Mon, 14 Feb 2022 21:29:51 +0000 Subject: KVM: x86: Add KVM_CAP_ENABLE_CAP to x86 Follow the precedent set by other architectures that support the VCPU ioctl, KVM_ENABLE_CAP, and advertise the VM extension, KVM_CAP_ENABLE_CAP. This way, userspace can ensure that KVM_ENABLE_CAP is available on a vcpu before using it. Fixes: 5c919412fe61 ("kvm/x86: Hyper-V synthetic interrupt controller") Signed-off-by: Aaron Lewis Message-Id: <20220214212950.1776943-1-aaronlewis@google.com> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini --- arch/x86/kvm/x86.c | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/x86') diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 641044db415d..b8bd8da32045 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4233,6 +4233,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) case KVM_CAP_EXIT_ON_EMULATION_FAILURE: case KVM_CAP_VCPU_ATTRIBUTES: case KVM_CAP_SYS_ATTRIBUTES: + case KVM_CAP_ENABLE_CAP: r = 1; break; case KVM_CAP_EXIT_HYPERCALL: -- cgit v1.2.3-70-g09d2 From 3a55f729240a686aa8af00af436306c0cd532522 Mon Sep 17 00:00:00 2001 From: Anton Romanov Date: Wed, 16 Feb 2022 18:26:54 +0000 Subject: kvm: x86: Disable KVM_HC_CLOCK_PAIRING if tsc is in always catchup mode If vcpu has tsc_always_catchup set each request updates pvclock data. KVM_HC_CLOCK_PAIRING consumers such as ptp_kvm_x86 rely on tsc read on host's side and do hypercall inside pvclock_read_retry loop leading to infinite loop in such situation. v3: Removed warn Changed return code to KVM_EFAULT v2: Added warn Signed-off-by: Anton Romanov Message-Id: <20220216182653.506850-1-romanton@google.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/x86.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'arch/x86') diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index b8bd8da32045..3471efe47e5f 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -8943,6 +8943,13 @@ static int kvm_pv_clock_pairing(struct kvm_vcpu *vcpu, gpa_t paddr, if (clock_type != KVM_CLOCK_PAIRING_WALLCLOCK) return -KVM_EOPNOTSUPP; + /* + * When tsc is in permanent catchup mode guests won't be able to use + * pvclock_read_retry loop to get consistent view of pvclock + */ + if (vcpu->arch.tsc_always_catchup) + return -KVM_EOPNOTSUPP; + if (!kvm_get_walltime_and_clockread(&ts, &cycle)) return -KVM_EOPNOTSUPP; -- cgit v1.2.3-70-g09d2 From ad856280ddea3401e1f5060ef20e6de9f6122c76 Mon Sep 17 00:00:00 2001 From: Leonardo Bras Date: Thu, 17 Feb 2022 02:30:29 -0300 Subject: x86/kvm/fpu: Limit guest user_xfeatures to supported bits of XCR0 During host/guest switch (like in kvm_arch_vcpu_ioctl_run()), the kernel swaps the fpu between host/guest contexts, by using fpu_swap_kvm_fpstate(). When xsave feature is available, the fpu swap is done by: - xsave(s) instruction, with guest's fpstate->xfeatures as mask, is used to store the current state of the fpu registers to a buffer. - xrstor(s) instruction, with (fpu_kernel_cfg.max_features & XFEATURE_MASK_FPSTATE) as mask, is used to put the buffer into fpu regs. For xsave(s) the mask is used to limit what parts of the fpu regs will be copied to the buffer. Likewise on xrstor(s), the mask is used to limit what parts of the fpu regs will be changed. The mask for xsave(s), the guest's fpstate->xfeatures, is defined on kvm_arch_vcpu_create(), which (in summary) sets it to all features supported by the cpu which are enabled on kernel config. This means that xsave(s) will save to guest buffer all the fpu regs contents the cpu has enabled when the guest is paused, even if they are not used. This would not be an issue, if xrstor(s) would also do that. xrstor(s)'s mask for host/guest swap is basically every valid feature contained in kernel config, except XFEATURE_MASK_PKRU. Accordingto kernel src, it is instead switched in switch_to() and flush_thread(). Then, the following happens with a host supporting PKRU starts a guest that does not support it: 1 - Host has XFEATURE_MASK_PKRU set. 1st switch to guest, 2 - xsave(s) fpu regs to host fpustate (buffer has XFEATURE_MASK_PKRU) 3 - xrstor(s) guest fpustate to fpu regs (fpu regs have XFEATURE_MASK_PKRU) 4 - guest runs, then switch back to host, 5 - xsave(s) fpu regs to guest fpstate (buffer now have XFEATURE_MASK_PKRU) 6 - xrstor(s) host fpstate to fpu regs. 7 - kvm_vcpu_ioctl_x86_get_xsave() copy guest fpstate to userspace (with XFEATURE_MASK_PKRU, which should not be supported by guest vcpu) On 5, even though the guest does not support PKRU, it does have the flag set on guest fpstate, which is transferred to userspace via vcpu ioctl KVM_GET_XSAVE. This becomes a problem when the user decides on migrating the above guest to another machine that does not support PKRU: the new host restores guest's fpu regs to as they were before (xrstor(s)), but since the new host don't support PKRU, a general-protection exception ocurs in xrstor(s) and that crashes the guest. This can be solved by making the guest's fpstate->user_xfeatures hold a copy of guest_supported_xcr0. This way, on 7 the only flags copied to userspace will be the ones compatible to guest requirements, and thus there will be no issue during migration. As a bonus, it will also fail if userspace tries to set fpu features (with the KVM_SET_XSAVE ioctl) that are not compatible to the guest configuration. Such features will never be returned by KVM_GET_XSAVE or KVM_GET_XSAVE2. Also, since kvm_vcpu_after_set_cpuid() now sets fpstate->user_xfeatures, there is not need to set it in kvm_check_cpuid(). So, change fpstate_realloc() so it does not touch fpstate->user_xfeatures if a non-NULL guest_fpu is passed, which is the case when kvm_check_cpuid() calls it. Signed-off-by: Leonardo Bras Message-Id: <20220217053028.96432-2-leobras@redhat.com> Signed-off-by: Paolo Bonzini --- arch/x86/kernel/fpu/xstate.c | 5 ++++- arch/x86/kvm/cpuid.c | 2 ++ 2 files changed, 6 insertions(+), 1 deletion(-) (limited to 'arch/x86') diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 02b3ddaf4f75..7c7824ae7862 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -1558,7 +1558,10 @@ static int fpstate_realloc(u64 xfeatures, unsigned int ksize, fpregs_restore_userregs(); newfps->xfeatures = curfps->xfeatures | xfeatures; - newfps->user_xfeatures = curfps->user_xfeatures | xfeatures; + + if (!guest_fpu) + newfps->user_xfeatures = curfps->user_xfeatures | xfeatures; + newfps->xfd = curfps->xfd & ~xfeatures; /* Do the final updates within the locked region */ diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 494d4d351859..71125291c578 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -296,6 +296,8 @@ static void kvm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu) vcpu->arch.guest_supported_xcr0 = cpuid_get_supported_xcr0(vcpu->arch.cpuid_entries, vcpu->arch.cpuid_nent); + vcpu->arch.guest_fpu.fpstate->user_xfeatures = vcpu->arch.guest_supported_xcr0; + kvm_update_pv_runtime(vcpu); vcpu->arch.maxphyaddr = cpuid_query_maxphyaddr(vcpu); -- cgit v1.2.3-70-g09d2 From 988896bb61827345c6d074dd5f2af1b7b008193f Mon Sep 17 00:00:00 2001 From: Leonardo Bras Date: Thu, 17 Feb 2022 02:30:30 -0300 Subject: x86/kvm/fpu: Remove kvm_vcpu_arch.guest_supported_xcr0 kvm_vcpu_arch currently contains the guest supported features in both guest_supported_xcr0 and guest_fpu.fpstate->user_xfeatures field. Currently both fields are set to the same value in kvm_vcpu_after_set_cpuid() and are not changed anywhere else after that. Since it's not good to keep duplicated data, remove guest_supported_xcr0. To keep the code more readable, introduce kvm_guest_supported_xcr() and kvm_guest_supported_xfd() to replace the previous usages of guest_supported_xcr0. Signed-off-by: Leonardo Bras Message-Id: <20220217053028.96432-3-leobras@redhat.com> Signed-off-by: Paolo Bonzini --- arch/x86/include/asm/kvm_host.h | 1 - arch/x86/kvm/cpuid.c | 5 +++-- arch/x86/kvm/x86.c | 18 +++++++++++++----- 3 files changed, 16 insertions(+), 8 deletions(-) (limited to 'arch/x86') diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 6dcccb304775..ec9830d2aabf 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -703,7 +703,6 @@ struct kvm_vcpu_arch { struct fpu_guest guest_fpu; u64 xcr0; - u64 guest_supported_xcr0; struct kvm_pio_request pio; void *pio_data; diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 71125291c578..b8f8d268d058 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -282,6 +282,7 @@ static void kvm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu) { struct kvm_lapic *apic = vcpu->arch.apic; struct kvm_cpuid_entry2 *best; + u64 guest_supported_xcr0; best = kvm_find_cpuid_entry(vcpu, 1, 0); if (best && apic) { @@ -293,10 +294,10 @@ static void kvm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu) kvm_apic_set_version(vcpu); } - vcpu->arch.guest_supported_xcr0 = + guest_supported_xcr0 = cpuid_get_supported_xcr0(vcpu->arch.cpuid_entries, vcpu->arch.cpuid_nent); - vcpu->arch.guest_fpu.fpstate->user_xfeatures = vcpu->arch.guest_supported_xcr0; + vcpu->arch.guest_fpu.fpstate->user_xfeatures = guest_supported_xcr0; kvm_update_pv_runtime(vcpu); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 3471efe47e5f..20ad6fe391bf 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -984,6 +984,16 @@ void kvm_load_host_xsave_state(struct kvm_vcpu *vcpu) } EXPORT_SYMBOL_GPL(kvm_load_host_xsave_state); +static inline u64 kvm_guest_supported_xcr0(struct kvm_vcpu *vcpu) +{ + return vcpu->arch.guest_fpu.fpstate->user_xfeatures; +} + +static inline u64 kvm_guest_supported_xfd(struct kvm_vcpu *vcpu) +{ + return kvm_guest_supported_xcr0(vcpu) & XFEATURE_MASK_USER_DYNAMIC; +} + static int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr) { u64 xcr0 = xcr; @@ -1003,7 +1013,7 @@ static int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr) * saving. However, xcr0 bit 0 is always set, even if the * emulated CPU does not support XSAVE (see kvm_vcpu_reset()). */ - valid_bits = vcpu->arch.guest_supported_xcr0 | XFEATURE_MASK_FP; + valid_bits = kvm_guest_supported_xcr0(vcpu) | XFEATURE_MASK_FP; if (xcr0 & ~valid_bits) return 1; @@ -3706,8 +3716,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) !guest_cpuid_has(vcpu, X86_FEATURE_XFD)) return 1; - if (data & ~(XFEATURE_MASK_USER_DYNAMIC & - vcpu->arch.guest_supported_xcr0)) + if (data & ~kvm_guest_supported_xfd(vcpu)) return 1; fpu_update_guest_xfd(&vcpu->arch.guest_fpu, data); @@ -3717,8 +3726,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) !guest_cpuid_has(vcpu, X86_FEATURE_XFD)) return 1; - if (data & ~(XFEATURE_MASK_USER_DYNAMIC & - vcpu->arch.guest_supported_xcr0)) + if (data & ~kvm_guest_supported_xfd(vcpu)) return 1; vcpu->arch.guest_fpu.xfd_err = data; -- cgit v1.2.3-70-g09d2 From ba1f77c546966c12d86220d078e5838dcaeab348 Mon Sep 17 00:00:00 2001 From: Leonardo Bras Date: Fri, 18 Feb 2022 00:41:00 -0300 Subject: x86/kvm: Fix compilation warning in non-x86_64 builds On non-x86_64 builds, helpers gtod_is_based_on_tsc() and kvm_guest_supported_xfd() are defined but never used. Because these are static inline but are in a .c file, some compilers do warn for them with -Wunused-function, which becomes an error if -Werror is present. Add #ifdef so they are only defined in x86_64 builds. Reported-by: kernel test robot Signed-off-by: Leonardo Bras Message-Id: <20220218034100.115702-1-leobras@redhat.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/x86.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'arch/x86') diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 20ad6fe391bf..82a9dcd8c67f 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -989,10 +989,12 @@ static inline u64 kvm_guest_supported_xcr0(struct kvm_vcpu *vcpu) return vcpu->arch.guest_fpu.fpstate->user_xfeatures; } +#ifdef CONFIG_X86_64 static inline u64 kvm_guest_supported_xfd(struct kvm_vcpu *vcpu) { return kvm_guest_supported_xcr0(vcpu) & XFEATURE_MASK_USER_DYNAMIC; } +#endif static int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr) { @@ -2361,10 +2363,12 @@ static u64 compute_guest_tsc(struct kvm_vcpu *vcpu, s64 kernel_ns) return tsc; } +#ifdef CONFIG_X86_64 static inline int gtod_is_based_on_tsc(int mode) { return mode == VDSO_CLOCKMODE_TSC || mode == VDSO_CLOCKMODE_HVCLOCK; } +#endif static void kvm_track_tsc_matching(struct kvm_vcpu *vcpu) { -- cgit v1.2.3-70-g09d2 From ec756e40e271866f951d77c5e923d8deb6002b15 Mon Sep 17 00:00:00 2001 From: Wanpeng Li Date: Fri, 18 Feb 2022 00:10:38 -0800 Subject: x86/kvm: Don't use pv tlb/ipi/sched_yield if on 1 vCPU Inspired by commit 3553ae5690a (x86/kvm: Don't use pvqspinlock code if only 1 vCPU), on a VM with only 1 vCPU, there is no need to enable pv tlb/ipi/sched_yield and we can save the memory for __pv_cpu_mask. Signed-off-by: Wanpeng Li Message-Id: <1645171838-2855-1-git-send-email-wanpengli@tencent.com> Signed-off-by: Paolo Bonzini --- arch/x86/kernel/kvm.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) (limited to 'arch/x86') diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index a438217cbfac..f734e3b0cfec 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -462,19 +462,22 @@ static bool pv_tlb_flush_supported(void) { return (kvm_para_has_feature(KVM_FEATURE_PV_TLB_FLUSH) && !kvm_para_has_hint(KVM_HINTS_REALTIME) && - kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)); + kvm_para_has_feature(KVM_FEATURE_STEAL_TIME) && + (num_possible_cpus() != 1)); } static bool pv_ipi_supported(void) { - return kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI); + return (kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI) && + (num_possible_cpus() != 1)); } static bool pv_sched_yield_supported(void) { return (kvm_para_has_feature(KVM_FEATURE_PV_SCHED_YIELD) && !kvm_para_has_hint(KVM_HINTS_REALTIME) && - kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)); + kvm_para_has_feature(KVM_FEATURE_STEAL_TIME) && + (num_possible_cpus() != 1)); } #define KVM_IPI_CLUSTER_SIZE (2 * BITS_PER_LONG) -- cgit v1.2.3-70-g09d2 From 6f3c1fc53d86d580d8d6d749c4af23705e4f6f79 Mon Sep 17 00:00:00 2001 From: Liang Zhang Date: Tue, 22 Feb 2022 11:12:39 +0800 Subject: KVM: x86/mmu: make apf token non-zero to fix bug In current async pagefault logic, when a page is ready, KVM relies on kvm_arch_can_dequeue_async_page_present() to determine whether to deliver a READY event to the Guest. This function test token value of struct kvm_vcpu_pv_apf_data, which must be reset to zero by Guest kernel when a READY event is finished by Guest. If value is zero meaning that a READY event is done, so the KVM can deliver another. But the kvm_arch_setup_async_pf() may produce a valid token with zero value, which is confused with previous mention and may lead the loss of this READY event. This bug may cause task blocked forever in Guest: INFO: task stress:7532 blocked for more than 1254 seconds. Not tainted 5.10.0 #16 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:stress state:D stack: 0 pid: 7532 ppid: 1409 flags:0x00000080 Call Trace: __schedule+0x1e7/0x650 schedule+0x46/0xb0 kvm_async_pf_task_wait_schedule+0xad/0xe0 ? exit_to_user_mode_prepare+0x60/0x70 __kvm_handle_async_pf+0x4f/0xb0 ? asm_exc_page_fault+0x8/0x30 exc_page_fault+0x6f/0x110 ? asm_exc_page_fault+0x8/0x30 asm_exc_page_fault+0x1e/0x30 RIP: 0033:0x402d00 RSP: 002b:00007ffd31912500 EFLAGS: 00010206 RAX: 0000000000071000 RBX: ffffffffffffffff RCX: 00000000021a32b0 RDX: 000000000007d011 RSI: 000000000007d000 RDI: 00000000021262b0 RBP: 00000000021262b0 R08: 0000000000000003 R09: 0000000000000086 R10: 00000000000000eb R11: 00007fefbdf2baa0 R12: 0000000000000000 R13: 0000000000000002 R14: 000000000007d000 R15: 0000000000001000 Signed-off-by: Liang Zhang Message-Id: <20220222031239.1076682-1-zhangliang5@huawei.com> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini --- arch/x86/kvm/mmu/mmu.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) (limited to 'arch/x86') diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 593093b52395..8e24f73bf60b 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -3889,12 +3889,23 @@ static void shadow_page_table_clear_flood(struct kvm_vcpu *vcpu, gva_t addr) walk_shadow_page_lockless_end(vcpu); } +static u32 alloc_apf_token(struct kvm_vcpu *vcpu) +{ + /* make sure the token value is not 0 */ + u32 id = vcpu->arch.apf.id; + + if (id << 12 == 0) + vcpu->arch.apf.id = 1; + + return (vcpu->arch.apf.id++ << 12) | vcpu->vcpu_id; +} + static bool kvm_arch_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, gfn_t gfn) { struct kvm_arch_async_pf arch; - arch.token = (vcpu->arch.apf.id++ << 12) | vcpu->vcpu_id; + arch.token = alloc_apf_token(vcpu); arch.gfn = gfn; arch.direct_map = vcpu->arch.mmu->direct_map; arch.cr3 = vcpu->arch.mmu->get_guest_pgd(vcpu); -- cgit v1.2.3-70-g09d2 From e910a53fb4f20aa012e46371ffb4c32c8da259b4 Mon Sep 17 00:00:00 2001 From: Maxim Levitsky Date: Wed, 23 Feb 2022 13:56:49 +0200 Subject: KVM: x86: nSVM: disallow userspace setting of MSR_AMD64_TSC_RATIO to non default value when tsc scaling disabled If nested tsc scaling is disabled, MSR_AMD64_TSC_RATIO should never have non default value. Due to way nested tsc scaling support was implmented in qemu, it would set this msr to 0 when nested tsc scaling was disabled. Ignore that value for now, as it causes no harm. Fixes: 5228eb96a487 ("KVM: x86: nSVM: implement nested TSC scaling") Cc: stable@vger.kernel.org Signed-off-by: Maxim Levitsky Message-Id: <20220223115649.319134-1-mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/svm/svm.c | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) (limited to 'arch/x86') diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 821edf664e7a..fd3a00c892c7 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -2693,8 +2693,23 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr) u64 data = msr->data; switch (ecx) { case MSR_AMD64_TSC_RATIO: - if (!msr->host_initiated && !svm->tsc_scaling_enabled) - return 1; + + if (!svm->tsc_scaling_enabled) { + + if (!msr->host_initiated) + return 1; + /* + * In case TSC scaling is not enabled, always + * leave this MSR at the default value. + * + * Due to bug in qemu 6.2.0, it would try to set + * this msr to 0 if tsc scaling is not enabled. + * Ignore this value as well. + */ + if (data != 0 && data != svm->tsc_ratio_msr) + return 1; + break; + } if (data & TSC_RATIO_RSVD) return 1; -- cgit v1.2.3-70-g09d2