Tianyu Lan <ltykernel@xxxxxxxxx> writes:
> From: Tianyu Lan <Tianyu.Lan@xxxxxxxxxxxxx>
>
> Hyper-V provides ghcb hvcall to handle VMBus
> HVCALL_SIGNAL_EVENT and HVCALL_POST_MESSAGE
> msg in SNP Isolation VM. Add such support.
>
> Signed-off-by: Tianyu Lan <Tianyu.Lan@xxxxxxxxxxxxx>
> ---
> arch/x86/hyperv/ivm.c | 69 +++++++++++++++++++++++++++++++++
> arch/x86/include/asm/mshyperv.h | 1 +
> drivers/hv/connection.c | 6 ++-
> drivers/hv/hv.c | 8 +++-
> 4 files changed, 82 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
> index 4332bf7aaf9b..feaabcd151f5 100644
> --- a/arch/x86/hyperv/ivm.c
> +++ b/arch/x86/hyperv/ivm.c
> @@ -14,8 +14,77 @@
>
> union hv_ghcb {
> struct ghcb ghcb;
> + struct {
> + u64 hypercalldata[509];
> + u64 outputgpa;
> + union {
> + union {
> + struct {
> + u32 callcode : 16;
> + u32 isfast : 1;
> + u32 reserved1 : 14;
> + u32 isnested : 1;
> + u32 countofelements : 12;
> + u32 reserved2 : 4;
> + u32 repstartindex : 12;
> + u32 reserved3 : 4;
> + };
> + u64 asuint64;
> + } hypercallinput;
> + union {
> + struct {
> + u16 callstatus;
> + u16 reserved1;
> + u32 elementsprocessed : 12;
> + u32 reserved2 : 20;
> + };
> + u64 asunit64;
> + } hypercalloutput;
> + };
> + u64 reserved2;
> + } hypercall;
> } __packed __aligned(PAGE_SIZE);
>
> +u64 hv_ghcb_hypercall(u64 control, void *input, void *output, u32 input_size)
> +{
> + union hv_ghcb *hv_ghcb;
> + void **ghcb_base;
> + unsigned long flags;
> +
> + if (!ms_hyperv.ghcb_base)
> + return -EFAULT;
> +
> + local_irq_save(flags);
> + ghcb_base = (void **)this_cpu_ptr(ms_hyperv.ghcb_base);
> + hv_ghcb = (union hv_ghcb *)*ghcb_base;
> + if (!hv_ghcb) {
> + local_irq_restore(flags);
> + return -EFAULT;
> + }
> +
> + memset(hv_ghcb, 0x00, HV_HYP_PAGE_SIZE);
> + hv_ghcb->ghcb.protocol_version = 1;
> + hv_ghcb->ghcb.ghcb_usage = 1;
> +
> + hv_ghcb->hypercall.outputgpa = (u64)output;
> + hv_ghcb->hypercall.hypercallinput.asuint64 = 0;
> + hv_ghcb->hypercall.hypercallinput.callcode = control;
> +
> + if (input_size)
> + memcpy(hv_ghcb->hypercall.hypercalldata, input, input_size);
> +
> + VMGEXIT();
> +
> + hv_ghcb->ghcb.ghcb_usage = 0xffffffff;
> + memset(hv_ghcb->ghcb.save.valid_bitmap, 0,
> + sizeof(hv_ghcb->ghcb.save.valid_bitmap));
> +
> + local_irq_restore(flags);
> +
> + return hv_ghcb->hypercall.hypercalloutput.callstatus;
> +}
> +EXPORT_SYMBOL_GPL(hv_ghcb_hypercall);
> +
> void hv_ghcb_msr_write(u64 msr, u64 value)
> {
> union hv_ghcb *hv_ghcb;
> diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
> index f624d72b99d3..c8f66d269e5b 100644
> --- a/arch/x86/include/asm/mshyperv.h
> +++ b/arch/x86/include/asm/mshyperv.h
> @@ -274,6 +274,7 @@ void hv_sint_rdmsrl_ghcb(u64 msr, u64 *value);
> void hv_signal_eom_ghcb(void);
> void hv_ghcb_msr_write(u64 msr, u64 value);
> void hv_ghcb_msr_read(u64 msr, u64 *value);
> +u64 hv_ghcb_hypercall(u64 control, void *input, void *output, u32 input_size);
>
> #define hv_get_synint_state_ghcb(int_num, val) \
> hv_sint_rdmsrl_ghcb(HV_X64_MSR_SINT0 + int_num, val)
> diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
> index c83612cddb99..79bca653dce9 100644
> --- a/drivers/hv/connection.c
> +++ b/drivers/hv/connection.c
> @@ -442,6 +442,10 @@ void vmbus_set_event(struct vmbus_channel *channel)
>
> ++channel->sig_events;
>
> - hv_do_fast_hypercall8(HVCALL_SIGNAL_EVENT, channel->sig_event);
> + if (hv_isolation_type_snp())
> + hv_ghcb_hypercall(HVCALL_SIGNAL_EVENT, &channel->sig_event,
> + NULL, sizeof(u64));
> + else
> + hv_do_fast_hypercall8(HVCALL_SIGNAL_EVENT, channel->sig_event);
vmbus_set_event() is a hotpath so I'd suggest we introduce a static
branch instead of checking hv_isolation_type_snp() every time.
> }
> EXPORT_SYMBOL_GPL(vmbus_set_event);
> diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
> index 28e28ccc2081..6c64a7fd1ebd 100644
> --- a/drivers/hv/hv.c
> +++ b/drivers/hv/hv.c
> @@ -60,7 +60,13 @@ int hv_post_message(union hv_connection_id connection_id,
> aligned_msg->payload_size = payload_size;
> memcpy((void *)aligned_msg->payload, payload, payload_size);
>
> - status = hv_do_hypercall(HVCALL_POST_MESSAGE, aligned_msg, NULL);
> + if (hv_isolation_type_snp())
> + status = hv_ghcb_hypercall(HVCALL_POST_MESSAGE,
> + (void *)aligned_msg, NULL,
> + sizeof(struct hv_input_post_message));
> + else
> + status = hv_do_hypercall(HVCALL_POST_MESSAGE,
> + aligned_msg, NULL);
and, if we are to introduce a static branch, we could use it here
(though it doesn't matter much for messages).
>
> /* Preemption must remain disabled until after the hypercall
> * so some other thread can't get scheduled onto this cpu and
--
Vitaly
