Re: [PART1 RFC v3 09/12] svm: Add VMEXIT handlers for AVIC

From: Paolo Bonzini
Date: Fri Mar 18 2016 - 07:11:45 EST

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In reply to: Suravee Suthikulpanit: "[PART1 RFC v3 09/12] svm: Add VMEXIT handlers for AVIC"
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On 18/03/2016 07:09, Suravee Suthikulpanit wrote:
> From: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>
>
> Introduce VMEXIT handlers, avic_incp_ipi_interception() and
> avic_noaccel_interception().

The names of the functions have changed.

> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>
> ---
> arch/x86/include/uapi/asm/svm.h | 9 +-
> arch/x86/kvm/lapic.h | 3 +
> arch/x86/kvm/svm.c | 244 ++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 255 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/include/uapi/asm/svm.h b/arch/x86/include/uapi/asm/svm.h
> index 8a4add8..131b0b9 100644
> --- a/arch/x86/include/uapi/asm/svm.h
> +++ b/arch/x86/include/uapi/asm/svm.h
> @@ -73,6 +73,8 @@
> #define SVM_EXIT_MWAIT_COND 0x08c
> #define SVM_EXIT_XSETBV 0x08d
> #define SVM_EXIT_NPF 0x400
> +#define SVM_EXIT_AVIC_INCOMPLETE_IPI 0x401
> +#define SVM_EXIT_AVIC_UNACCELERATED_ACCESS 0x402
>
> #define SVM_EXIT_ERR -1
>
> @@ -107,8 +109,10 @@
> { SVM_EXIT_SMI, "smi" }, \
> { SVM_EXIT_INIT, "init" }, \
> { SVM_EXIT_VINTR, "vintr" }, \
> + { SVM_EXIT_CR0_SEL_WRITE, "cr0_sec_write" }, \

sel_write.

> { SVM_EXIT_CPUID, "cpuid" }, \
> { SVM_EXIT_INVD, "invd" }, \
> + { SVM_EXIT_PAUSE, "pause" }, \
> { SVM_EXIT_HLT, "hlt" }, \
> { SVM_EXIT_INVLPG, "invlpg" }, \
> { SVM_EXIT_INVLPGA, "invlpga" }, \
> @@ -127,7 +131,10 @@
> { SVM_EXIT_MONITOR, "monitor" }, \
> { SVM_EXIT_MWAIT, "mwait" }, \
> { SVM_EXIT_XSETBV, "xsetbv" }, \
> - { SVM_EXIT_NPF, "npf" }
> + { SVM_EXIT_NPF, "npf" }, \
> + { SVM_EXIT_RSM, "rsm" }, \
> + { SVM_EXIT_AVIC_INCOMPLETE_IPI, "avic_incomplete_ipi" }, \
> + { SVM_EXIT_AVIC_UNACCELERATED_ACCESS, "avic_unaccelerated_access" }
>
>
> #endif /* _UAPI__SVM_H */
> diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
> index 7bf8184..ed23af0 100644
> --- a/arch/x86/kvm/lapic.h
> +++ b/arch/x86/kvm/lapic.h
> @@ -9,6 +9,9 @@
> #define KVM_APIC_SIPI 1
> #define KVM_APIC_LVT_NUM 6
>
> +#define KVM_APIC_SHORT_MASK 0xc0000
> +#define KVM_APIC_DEST_MASK 0x800
> +
> struct kvm_timer {
> struct hrtimer timer;
> s64 period; /* unit: ns */
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index 8e31ad3..6303147 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -3508,6 +3508,248 @@ static int mwait_interception(struct vcpu_svm *svm)
> return nop_interception(svm);
> }
>
> +enum avic_ipi_failure_cause {
> + AVIC_IPI_FAILURE_INVALID_INT_TYPE,
> + AVIC_IPI_FAILURE_TARGET_NOT_RUNNING,
> + AVIC_IPI_FAILURE_INVALID_TARGET,
> + AVIC_IPI_FAILURE_INVALID_BACKING_PAGE,
> +};
> +
> +static int avic_incomplete_ipi_interception(struct vcpu_svm *svm)
> +{
> + u32 icrh = svm->vmcb->control.exit_info_1 >> 32;
> + u32 icrl = svm->vmcb->control.exit_info_1;
> + u32 id = svm->vmcb->control.exit_info_2 >> 32;
> + u32 index = svm->vmcb->control.exit_info_2 && 0xFF;
> + struct kvm_lapic *apic = svm->vcpu.arch.apic;
> +
> + trace_kvm_avic_incomplete_ipi(svm->vcpu.vcpu_id, icrh, icrl, id, index);
> +
> + switch (id) {
> + case AVIC_IPI_FAILURE_INVALID_INT_TYPE:
> + /*
> + * AVIC hardware handles the generation of
> + * IPIs when the specified Message Type is Fixed
> + * (also known as fixed delivery mode) and
> + * the Trigger Mode is edge-triggered. The hardware
> + * also supports self and broadcast delivery modes
> + * specified via the Destination Shorthand(DSH)
> + * field of the ICRL. Logical and physical APIC ID
> + * formats are supported. All other IPI types cause
> + * a #VMEXIT, which needs to emulated.
> + */
> + kvm_lapic_reg_write(apic, APIC_ICR2, icrh);
> + kvm_lapic_reg_write(apic, APIC_ICR, icrl);
> + break;
> + case AVIC_IPI_FAILURE_TARGET_NOT_RUNNING: {
> + int i;
> + struct kvm_vcpu *vcpu;
> + struct kvm *kvm = svm->vcpu.kvm;
> + struct kvm_lapic *apic = svm->vcpu.arch.apic;
> +
> + /*
> + * At this point, we expect that the AVIC HW has already
> + * set the appropriate IRR bits on the valid target
> + * vcpus. So, we just need to kick the appropriate vcpu.
> + */
> + kvm_for_each_vcpu(i, vcpu, kvm) {
> + bool m = kvm_apic_match_dest(vcpu, apic,
> + icrl & KVM_APIC_SHORT_MASK,
> + GET_APIC_DEST_FIELD(icrh),
> + icrl & KVM_APIC_DEST_MASK);
> +
> + if (m && !avic_vcpu_is_running(vcpu))
> + kvm_vcpu_wake_up(vcpu);
> + }
> + break;
> + }
> + case AVIC_IPI_FAILURE_INVALID_TARGET:
> + break;
> + case AVIC_IPI_FAILURE_INVALID_BACKING_PAGE:
> + WARN_ONCE(1, "Invalid backing page\n");
> + break;
> + default:
> + pr_err("Unknown IPI interception\n");
> + }
> +
> + return 1;
> +}
> +
> +static u32 *avic_get_log_apic_id_entry(struct kvm_vcpu *vcpu, u8 mda, bool flat)
> +{
> + struct kvm_arch *vm_data = &vcpu->kvm->arch;
> + int index;
> + u32 *avic_log_ait;

u32 *logical_apic_id_table;

> +
> + if (flat) { /* flat */
> + if (mda > 7)
> + return NULL;
> + index = mda;
> + } else { /* cluster */
> + int apic_id = mda & 0xf;
> + int cluster_id = (mda & 0xf0) >> 8;
> +
> + if (apic_id > 4 || cluster_id >= 0xf)
> + return NULL;
> + index = (cluster_id << 2) + apic_id;
> + }
> + avic_log_ait = (u32 *) page_address(vm_data->avic_log_apic_id_table_page);
> +
> + return &avic_log_ait[index];
> +}
> +
> +static int avic_handle_ldr_write(struct kvm_vcpu *vcpu, u8 g_phy_apic_id,
> + u8 log_apic_id)
> +{
> + u32 mod;
> + u32 *entry;
> + struct vcpu_svm *svm = to_svm(vcpu);
> +
> + if (!svm)
> + return -EINVAL;
> +
> + mod = (kvm_apic_get_reg(svm->vcpu.arch.apic, APIC_DFR) >> 28) & 0xf;
> + entry = avic_get_log_apic_id_entry(vcpu, log_apic_id, (mod == 0xf));
> + if (!entry)
> + return -EINVAL;
> +
> + *entry &= ~AVIC_LOG_APIC_ID__GUEST_PHY_APIC_ID_MSK;
> + *entry |= (g_phy_apic_id & AVIC_LOG_APIC_ID__GUEST_PHY_APIC_ID_MSK);
> + *entry |= AVIC_LOG_APIC_ID__VALID_MSK;

I think you should do these computations in a separate u32 variable and
then assign it to *entry.

Apart from these, it looks pretty good!

Paolo

> + return 0;
> +}
> +
> +static int avic_unaccel_trap_write(struct vcpu_svm *svm)
> +{
> + u32 offset = svm->vmcb->control.exit_info_1 & 0xFF0;
> + struct kvm_lapic *apic = svm->vcpu.arch.apic;
> + u32 reg = kvm_apic_get_reg(apic, offset);
> +
> + switch (offset) {
> + case APIC_ID: {
> + u32 aid = (reg >> 24) & 0xff;
> + u64 *o_ent = avic_get_phy_apic_id_entry(&svm->vcpu,
> + svm->vcpu.vcpu_id);
> + u64 *n_ent = avic_get_phy_apic_id_entry(&svm->vcpu, aid);
> +
> + if (!n_ent || !o_ent)
> + return 0;
> +
> + /* We need to move phy_apic_entry to new offset */
> + *n_ent = *o_ent;
> + *((u64 *)o_ent) = 0ULL;

Unnecessary cast.

> + svm->avic_phy_apic_id_cache = n_ent;
> + break;
> + }
> + case APIC_LDR: {
> + int ret, lid;
> + int dlid = (reg >> 24) & 0xff;
> +
> + if (!dlid)
> + return 0;
> +
> + lid = ffs(dlid) - 1;
> + ret = avic_handle_ldr_write(&svm->vcpu, svm->vcpu.vcpu_id, lid);
> + if (ret)
> + return 0;
> +
> + break;
> + }
> + case APIC_DFR: {
> + struct kvm_arch *vm_data = &svm->vcpu.kvm->arch;
> + u32 mod = (reg >> 28) & 0xf;
> +
> + /*
> + * We assume that all local APICs are using the same type.
> + * If this changes, we need to rebuild the AVIC logical
> + * APID id table with subsequent write to APIC_LDR.
> + */
> + if (vm_data->ldr_mode != mod) {
> + clear_page(page_address(vm_data->avic_log_apic_id_table_page));
> + vm_data->ldr_mode = mod;
> + }
> + break;
> + }
> + default:
> + break;
> + }
> +
> + kvm_lapic_reg_write(apic, offset, reg);
> +
> + return 1;
> +}
> +
> +static bool is_avic_unaccelerated_access_trap(u32 offset)
> +{
> + bool ret = false;
> +
> + switch (offset) {
> + case APIC_ID:
> + case APIC_EOI:
> + case APIC_RRR:
> + case APIC_LDR:
> + case APIC_DFR:
> + case APIC_SPIV:
> + case APIC_ESR:
> + case APIC_ICR:
> + case APIC_LVTT:
> + case APIC_LVTTHMR:
> + case APIC_LVTPC:
> + case APIC_LVT0:
> + case APIC_LVT1:
> + case APIC_LVTERR:
> + case APIC_TMICT:
> + case APIC_TDCR:
> + ret = true;
> + break;
> + default:
> + break;
> + }
> + return ret;
> +}
> +
> +#define AVIC_UNACCEL_ACCESS_WRITE_MSK 1
> +#define AVIC_UNACCEL_ACCESS_OFFSET_MSK 0xFF0
> +#define AVIC_UNACCEL_ACCESS_VECTOR_MSK 0xFFFFFFFF
> +
> +static int avic_unaccelerated_access_interception(struct vcpu_svm *svm)
> +{
> + int ret = 0;
> + u32 offset = svm->vmcb->control.exit_info_1 &
> + AVIC_UNACCEL_ACCESS_OFFSET_MSK;
> + u32 vector = svm->vmcb->control.exit_info_2 &
> + AVIC_UNACCEL_ACCESS_VECTOR_MSK;
> + bool write = (svm->vmcb->control.exit_info_1 >> 32) &
> + AVIC_UNACCEL_ACCESS_WRITE_MSK;
> + bool trap = is_avic_unaccelerated_access_trap(offset);
> +
> + trace_kvm_avic_unaccelerated_access(svm->vcpu.vcpu_id, offset,
> + trap, write, vector);
> +
> + /**
> + * AVIC does not support x2APIC registers, and we only advertise
> + * xAPIC when enable AVIC. Therefore, access to these registers
> + * will not be supported.
> + */
> + if (offset >= 0x400) {
> + WARN(1, "Unsupported APIC offset %#x\n", offset);
> + return ret;
> + }
> +
> + if (trap) {
> + /* Handling Trap */
> + if (!write) /* Trap read should never happens */
> + BUG();
> + ret = avic_unaccel_trap_write(svm);
> + } else {
> + /* Handling Fault */
> + ret = (emulate_instruction(&svm->vcpu, 0) == EMULATE_DONE);
> + }
> +
> + return ret;
> +}
> +
> static int (*const svm_exit_handlers[])(struct vcpu_svm *svm) = {
> [SVM_EXIT_READ_CR0] = cr_interception,
> [SVM_EXIT_READ_CR3] = cr_interception,
> @@ -3571,6 +3813,8 @@ static int (*const svm_exit_handlers[])(struct vcpu_svm *svm) = {
> [SVM_EXIT_XSETBV] = xsetbv_interception,
> [SVM_EXIT_NPF] = pf_interception,
> [SVM_EXIT_RSM] = emulate_on_interception,
> + [SVM_EXIT_AVIC_INCOMPLETE_IPI] = avic_incomplete_ipi_interception,
> + [SVM_EXIT_AVIC_UNACCELERATED_ACCESS] = avic_unaccelerated_access_interception,
> };
>
> static void dump_vmcb(struct kvm_vcpu *vcpu)
>

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In reply to: Suravee Suthikulpanit: "[PART1 RFC v3 09/12] svm: Add VMEXIT handlers for AVIC"
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