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    SubjectRe: [PATCH v5 3/7] KVM: x86: hyper-v: Move the remote TLB flush logic out of vmx
    Date
    Vineeth Pillai <viremana@linux.microsoft.com> 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@linux.microsoft.com>
    > ---
    > 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

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