Re: [PATCH v5 3/7] KVM: x86: hyper-v: Move the remote TLB flush logic out of vmx

From: Vitaly Kuznetsov
Date: Thu Jun 10 2021 - 07:20:31 EST

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Vineeth Pillai <viremana@xxxxxxxxxxxxxxxxxxx> writes:

> Currently the remote TLB flush logic is specific to VMX.
> Move it to a common place so that SVM can use it as well.
>
> Signed-off-by: Vineeth Pillai <viremana@xxxxxxxxxxxxxxxxxxx>
> ---
> arch/x86/include/asm/kvm_host.h | 9 +++
> arch/x86/kvm/Makefile | 5 ++
> arch/x86/kvm/kvm_onhyperv.c | 93 ++++++++++++++++++++++++++++
> arch/x86/kvm/kvm_onhyperv.h | 32 ++++++++++
> arch/x86/kvm/vmx/vmx.c | 105 +-------------------------------
> arch/x86/kvm/vmx/vmx.h | 9 ---
> arch/x86/kvm/x86.c | 9 +++
> 7 files changed, 150 insertions(+), 112 deletions(-)
> create mode 100644 arch/x86/kvm/kvm_onhyperv.c
> create mode 100644 arch/x86/kvm/kvm_onhyperv.h
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index cbbcee0a84f9..bab305230e8d 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -849,6 +849,10 @@ struct kvm_vcpu_arch {
>
> /* Protected Guests */
> bool guest_state_protected;
> +
> +#if IS_ENABLED(CONFIG_HYPERV)
> + hpa_t hv_root_tdp;
> +#endif
> };
>
> struct kvm_lpage_info {
> @@ -1122,6 +1126,11 @@ struct kvm_arch {
> */
> spinlock_t tdp_mmu_pages_lock;
> #endif /* CONFIG_X86_64 */
> +
> +#if IS_ENABLED(CONFIG_HYPERV)
> + hpa_t hv_root_tdp;
> + spinlock_t hv_root_tdp_lock;
> +#endif
> };
>
> struct kvm_vm_stat {
> diff --git a/arch/x86/kvm/Makefile b/arch/x86/kvm/Makefile
> index c589db5d91b3..a06745c2fef1 100644
> --- a/arch/x86/kvm/Makefile
> +++ b/arch/x86/kvm/Makefile
> @@ -18,6 +18,11 @@ kvm-y += x86.o emulate.o i8259.o irq.o lapic.o \
> i8254.o ioapic.o irq_comm.o cpuid.o pmu.o mtrr.o \
> hyperv.o debugfs.o mmu/mmu.o mmu/page_track.o \
> mmu/spte.o
> +
> +ifdef CONFIG_HYPERV
> +kvm-y += kvm_onhyperv.o
> +endif
> +
> kvm-$(CONFIG_X86_64) += mmu/tdp_iter.o mmu/tdp_mmu.o
> kvm-$(CONFIG_KVM_XEN) += xen.o
>
> diff --git a/arch/x86/kvm/kvm_onhyperv.c b/arch/x86/kvm/kvm_onhyperv.c
> new file mode 100644
> index 000000000000..c7db2df50a7a
> --- /dev/null
> +++ b/arch/x86/kvm/kvm_onhyperv.c
> @@ -0,0 +1,93 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * KVM L1 hypervisor optimizations on Hyper-V.
> + */
> +
> +#include <linux/kvm_host.h>
> +#include <asm/mshyperv.h>
> +
> +#include "hyperv.h"
> +#include "kvm_onhyperv.h"
> +
> +static int kvm_fill_hv_flush_list_func(struct hv_guest_mapping_flush_list *flush,
> + void *data)
> +{
> + struct kvm_tlb_range *range = data;
> +
> + return hyperv_fill_flush_guest_mapping_list(flush, range->start_gfn,
> + range->pages);
> +}
> +
> +static inline int hv_remote_flush_root_tdp(hpa_t root_tdp,
> + struct kvm_tlb_range *range)
> +{
> + if (range)
> + return hyperv_flush_guest_mapping_range(root_tdp,
> + kvm_fill_hv_flush_list_func, (void *)range);
> + else
> + return hyperv_flush_guest_mapping(root_tdp);
> +}
> +
> +int hv_remote_flush_tlb_with_range(struct kvm *kvm,
> + struct kvm_tlb_range *range)
> +{
> + struct kvm_arch *kvm_arch = &kvm->arch;
> + struct kvm_vcpu *vcpu;
> + int ret = 0, i, nr_unique_valid_roots;
> + hpa_t root;
> +
> + spin_lock(&kvm_arch->hv_root_tdp_lock);
> +
> + if (!VALID_PAGE(kvm_arch->hv_root_tdp)) {
> + nr_unique_valid_roots = 0;
> +
> + /*
> + * Flush all valid roots, and see if all vCPUs have converged
> + * on a common root, in which case future flushes can skip the
> + * loop and flush the common root.
> + */
> + kvm_for_each_vcpu(i, vcpu, kvm) {
> + root = vcpu->arch.hv_root_tdp;
> + if (!VALID_PAGE(root) || root == kvm_arch->hv_root_tdp)
> + continue;
> +
> + /*
> + * Set the tracked root to the first valid root. Keep
> + * this root for the entirety of the loop even if more
> + * roots are encountered as a low effort optimization
> + * to avoid flushing the same (first) root again.
> + */
> + if (++nr_unique_valid_roots == 1)
> + kvm_arch->hv_root_tdp = root;
> +
> + if (!ret)
> + ret = hv_remote_flush_root_tdp(root, range);
> +
> + /*
> + * Stop processing roots if a failure occurred and
> + * multiple valid roots have already been detected.
> + */
> + if (ret && nr_unique_valid_roots > 1)
> + break;
> + }
> +
> + /*
> + * The optimized flush of a single root can't be used if there
> + * are multiple valid roots (obviously).
> + */
> + if (nr_unique_valid_roots > 1)
> + kvm_arch->hv_root_tdp = INVALID_PAGE;
> + } else {
> + ret = hv_remote_flush_root_tdp(kvm_arch->hv_root_tdp, range);
> + }
> +
> + spin_unlock(&kvm_arch->hv_root_tdp_lock);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(hv_remote_flush_tlb_with_range);
> +
> +int hv_remote_flush_tlb(struct kvm *kvm)
> +{
> + return hv_remote_flush_tlb_with_range(kvm, NULL);
> +}
> +EXPORT_SYMBOL_GPL(hv_remote_flush_tlb);
> diff --git a/arch/x86/kvm/kvm_onhyperv.h b/arch/x86/kvm/kvm_onhyperv.h
> new file mode 100644
> index 000000000000..c03f01024a70
> --- /dev/null
> +++ b/arch/x86/kvm/kvm_onhyperv.h
> @@ -0,0 +1,32 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * KVM L1 hypervisor optimizations on Hyper-V.
> + */
> +
> +#ifndef __ARCH_X86_KVM_KVM_ONHYPERV_H__
> +#define __ARCH_X86_KVM_KVM_ONHYPERV_H__
> +
> +#if IS_ENABLED(CONFIG_HYPERV)
> +int hv_remote_flush_tlb_with_range(struct kvm *kvm,
> + struct kvm_tlb_range *range);
> +int hv_remote_flush_tlb(struct kvm *kvm);
> +
> +static inline void hv_track_root_tdp(struct kvm_vcpu *vcpu, hpa_t root_tdp)
> +{
> + struct kvm_arch *kvm_arch = &vcpu->kvm->arch;
> +
> + if (kvm_x86_ops.tlb_remote_flush == hv_remote_flush_tlb) {
> + spin_lock(&kvm_arch->hv_root_tdp_lock);
> + vcpu->arch.hv_root_tdp = root_tdp;
> + if (root_tdp != kvm_arch->hv_root_tdp)
> + kvm_arch->hv_root_tdp = INVALID_PAGE;
> + spin_unlock(&kvm_arch->hv_root_tdp_lock);
> + }
> +}
> +#else
> +static inline void hv_track_root_tdp(struct kvm_vcpu *vcpu, hpa_t root_tdp)
> +{
> +}
> +#endif
> +#endif

Super-nitpick: I'd suggest adding /* __ARCH_X86_KVM_KVM_ONHYPERV_H__ */
to the second '#endif' and /* IS_ENABLED(CONFIG_HYPERV) */ to '#else'
and the first one: files/functions tend to grow and it becomes hard to
see where the particular '#endif/#else' belongs.

> +
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index d000cddbd734..117fb88cd354 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -52,6 +52,7 @@
> #include "cpuid.h"
> #include "evmcs.h"
> #include "hyperv.h"
> +#include "kvm_onhyperv.h"
> #include "irq.h"
> #include "kvm_cache_regs.h"
> #include "lapic.h"
> @@ -474,86 +475,6 @@ static const u32 vmx_uret_msrs_list[] = {
> static bool __read_mostly enlightened_vmcs = true;
> module_param(enlightened_vmcs, bool, 0444);
>
> -static int kvm_fill_hv_flush_list_func(struct hv_guest_mapping_flush_list *flush,
> - void *data)
> -{
> - struct kvm_tlb_range *range = data;
> -
> - return hyperv_fill_flush_guest_mapping_list(flush, range->start_gfn,
> - range->pages);
> -}
> -
> -static inline int hv_remote_flush_root_ept(hpa_t root_ept,
> - struct kvm_tlb_range *range)
> -{
> - if (range)
> - return hyperv_flush_guest_mapping_range(root_ept,
> - kvm_fill_hv_flush_list_func, (void *)range);
> - else
> - return hyperv_flush_guest_mapping(root_ept);
> -}
> -
> -static int hv_remote_flush_tlb_with_range(struct kvm *kvm,
> - struct kvm_tlb_range *range)
> -{
> - struct kvm_vmx *kvm_vmx = to_kvm_vmx(kvm);
> - struct kvm_vcpu *vcpu;
> - int ret = 0, i, nr_unique_valid_roots;
> - hpa_t root;
> -
> - spin_lock(&kvm_vmx->hv_root_ept_lock);
> -
> - if (!VALID_PAGE(kvm_vmx->hv_root_ept)) {
> - nr_unique_valid_roots = 0;
> -
> - /*
> - * Flush all valid roots, and see if all vCPUs have converged
> - * on a common root, in which case future flushes can skip the
> - * loop and flush the common root.
> - */
> - kvm_for_each_vcpu(i, vcpu, kvm) {
> - root = to_vmx(vcpu)->hv_root_ept;
> - if (!VALID_PAGE(root) || root == kvm_vmx->hv_root_ept)
> - continue;
> -
> - /*
> - * Set the tracked root to the first valid root. Keep
> - * this root for the entirety of the loop even if more
> - * roots are encountered as a low effort optimization
> - * to avoid flushing the same (first) root again.
> - */
> - if (++nr_unique_valid_roots == 1)
> - kvm_vmx->hv_root_ept = root;
> -
> - if (!ret)
> - ret = hv_remote_flush_root_ept(root, range);
> -
> - /*
> - * Stop processing roots if a failure occurred and
> - * multiple valid roots have already been detected.
> - */
> - if (ret && nr_unique_valid_roots > 1)
> - break;
> - }
> -
> - /*
> - * The optimized flush of a single root can't be used if there
> - * are multiple valid roots (obviously).
> - */
> - if (nr_unique_valid_roots > 1)
> - kvm_vmx->hv_root_ept = INVALID_PAGE;
> - } else {
> - ret = hv_remote_flush_root_ept(kvm_vmx->hv_root_ept, range);
> - }
> -
> - spin_unlock(&kvm_vmx->hv_root_ept_lock);
> - return ret;
> -}
> -static int hv_remote_flush_tlb(struct kvm *kvm)
> -{
> - return hv_remote_flush_tlb_with_range(kvm, NULL);
> -}
> -
> static int hv_enable_direct_tlbflush(struct kvm_vcpu *vcpu)
> {
> struct hv_enlightened_vmcs *evmcs;
> @@ -581,21 +502,6 @@ static int hv_enable_direct_tlbflush(struct kvm_vcpu *vcpu)
>
> #endif /* IS_ENABLED(CONFIG_HYPERV) */
>
> -static void hv_track_root_ept(struct kvm_vcpu *vcpu, hpa_t root_ept)
> -{
> -#if IS_ENABLED(CONFIG_HYPERV)
> - struct kvm_vmx *kvm_vmx = to_kvm_vmx(vcpu->kvm);
> -
> - if (kvm_x86_ops.tlb_remote_flush == hv_remote_flush_tlb) {
> - spin_lock(&kvm_vmx->hv_root_ept_lock);
> - to_vmx(vcpu)->hv_root_ept = root_ept;
> - if (root_ept != kvm_vmx->hv_root_ept)
> - kvm_vmx->hv_root_ept = INVALID_PAGE;
> - spin_unlock(&kvm_vmx->hv_root_ept_lock);
> - }
> -#endif
> -}
> -
> /*
> * Comment's format: document - errata name - stepping - processor name.
> * Refer from
> @@ -3202,7 +3108,7 @@ static void vmx_load_mmu_pgd(struct kvm_vcpu *vcpu, hpa_t root_hpa,
> eptp = construct_eptp(vcpu, root_hpa, root_level);
> vmcs_write64(EPT_POINTER, eptp);
>
> - hv_track_root_ept(vcpu, root_hpa);
> + hv_track_root_tdp(vcpu, root_hpa);
>
> if (!enable_unrestricted_guest && !is_paging(vcpu))
> guest_cr3 = to_kvm_vmx(kvm)->ept_identity_map_addr;
> @@ -6980,9 +6886,6 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu)
> vmx->pi_desc.nv = POSTED_INTR_VECTOR;
> vmx->pi_desc.sn = 1;
>
> -#if IS_ENABLED(CONFIG_HYPERV)
> - vmx->hv_root_ept = INVALID_PAGE;
> -#endif
> return 0;
>
> free_vmcs:
> @@ -6999,10 +6902,6 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu)
>
> static int vmx_vm_init(struct kvm *kvm)
> {
> -#if IS_ENABLED(CONFIG_HYPERV)
> - spin_lock_init(&to_kvm_vmx(kvm)->hv_root_ept_lock);
> -#endif
> -
> if (!ple_gap)
> kvm->arch.pause_in_guest = true;
>
> diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
> index 008cb87ff088..d1363e734a01 100644
> --- a/arch/x86/kvm/vmx/vmx.h
> +++ b/arch/x86/kvm/vmx/vmx.h
> @@ -328,10 +328,6 @@ struct vcpu_vmx {
> /* SGX Launch Control public key hash */
> u64 msr_ia32_sgxlepubkeyhash[4];
>
> -#if IS_ENABLED(CONFIG_HYPERV)
> - u64 hv_root_ept;
> -#endif
> -
> struct pt_desc pt_desc;
> struct lbr_desc lbr_desc;
>
> @@ -349,11 +345,6 @@ struct kvm_vmx {
> unsigned int tss_addr;
> bool ept_identity_pagetable_done;
> gpa_t ept_identity_map_addr;
> -
> -#if IS_ENABLED(CONFIG_HYPERV)
> - hpa_t hv_root_ept;
> - spinlock_t hv_root_ept_lock;
> -#endif
> };
>
> bool nested_vmx_allowed(struct kvm_vcpu *vcpu);
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 6eda2834fc05..580f3c6c86f9 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -10279,6 +10279,10 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
> vcpu->arch.pending_external_vector = -1;
> vcpu->arch.preempted_in_kernel = false;
>
> +#if IS_ENABLED(CONFIG_HYPERV)
> + vcpu->arch.hv_root_tdp = INVALID_PAGE;
> +#endif
> +
> r = static_call(kvm_x86_vcpu_create)(vcpu);
> if (r)
> goto free_guest_fpu;
> @@ -10662,6 +10666,11 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
>
> kvm->arch.guest_can_read_msr_platform_info = true;
>
> +#if IS_ENABLED(CONFIG_HYPERV)
> + spin_lock_init(&kvm->arch.hv_root_tdp_lock);
> + kvm->arch.hv_root_tdp = INVALID_PAGE;
> +#endif
> +
> INIT_DELAYED_WORK(&kvm->arch.kvmclock_update_work, kvmclock_update_fn);
> INIT_DELAYED_WORK(&kvm->arch.kvmclock_sync_work, kvmclock_sync_fn);

--
Vitaly

Next message: kernel test robot: "[rcu:clocksource] BUILD SUCCESS 023766fbdde49c75c13acd268bf9af810d624c59"
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