RE: [PATCH 2/2] drivers: hv: Create a consistent pattern for checking Hyper-V hypercall status

[Michael Kelley <mikelley@microsoft.com>]

From: Joseph Salisbury <joseph.salisbury@linux.microsoft.com> Sent: Friday, April 16, 2021 5:43 PM
> 
> There is not a consistent pattern for checking Hyper-V hypercall status.
> Existing code uses a number of variants.  The variants work, but a consistent
> pattern would improve the readability of the code, and be more conformant
> to what the Hyper-V TLFS says about hypercall status.
> 
> Implemented new helper functions hv_result(), hv_result_success(), and
> hv_repcomp().  Changed the places where hv_do_hypercall() and related variants
> are used to use the helper functions.
> 
> Signed-off-by: Joseph Salisbury <joseph.salisbury@microsoft.com>
> ---
>  arch/x86/hyperv/hv_apic.c           | 16 +++++++++-------
>  arch/x86/hyperv/hv_init.c           |  2 +-
>  arch/x86/hyperv/hv_proc.c           | 25 ++++++++++---------------
>  arch/x86/hyperv/irqdomain.c         |  6 +++---
>  arch/x86/hyperv/mmu.c               |  8 ++++----
>  arch/x86/hyperv/nested.c            |  8 ++++----
>  arch/x86/include/asm/mshyperv.h     |  1 +
>  drivers/hv/hv.c                     |  2 +-
>  drivers/pci/controller/pci-hyperv.c |  2 +-
>  include/asm-generic/mshyperv.h      | 25 ++++++++++++++++++++-----
>  10 files changed, 54 insertions(+), 41 deletions(-)

Wei -- I have gone through these changes reasonably carefully, but
your review of the Linux-in-the-root-partition changes would be a good
double-check.  It's too easy to get the sense of the tests backwards. :-(

Reviewed-by: Michael Kelley <mikelley@microsoft.com>

> 
> diff --git a/arch/x86/hyperv/hv_apic.c b/arch/x86/hyperv/hv_apic.c
> index 284e73661a18..ca581b24974a 100644
> --- a/arch/x86/hyperv/hv_apic.c
> +++ b/arch/x86/hyperv/hv_apic.c
> @@ -103,7 +103,7 @@ static bool __send_ipi_mask_ex(const struct cpumask *mask, int
> vector)
>  	struct hv_send_ipi_ex *ipi_arg;
>  	unsigned long flags;
>  	int nr_bank = 0;
> -	int ret = 1;
> +	u64 status = HV_STATUS_INVALID_PARAMETER;
> 
>  	if (!(ms_hyperv.hints & HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED))
>  		return false;
> @@ -128,19 +128,19 @@ static bool __send_ipi_mask_ex(const struct cpumask *mask, int
> vector)
>  	if (!nr_bank)
>  		ipi_arg->vp_set.format = HV_GENERIC_SET_ALL;
> 
> -	ret = hv_do_rep_hypercall(HVCALL_SEND_IPI_EX, 0, nr_bank,
> +	status = hv_do_rep_hypercall(HVCALL_SEND_IPI_EX, 0, nr_bank,
>  			      ipi_arg, NULL);
> 
>  ipi_mask_ex_done:
>  	local_irq_restore(flags);
> -	return ((ret == 0) ? true : false);
> +	return hv_result_success(status);
>  }
> 
>  static bool __send_ipi_mask(const struct cpumask *mask, int vector)
>  {
>  	int cur_cpu, vcpu;
>  	struct hv_send_ipi ipi_arg;
> -	int ret = 1;
> +	u64 status;
> 
>  	trace_hyperv_send_ipi_mask(mask, vector);
> 
> @@ -184,9 +184,9 @@ static bool __send_ipi_mask(const struct cpumask *mask, int
> vector)
>  		__set_bit(vcpu, (unsigned long *)&ipi_arg.cpu_mask);
>  	}
> 
> -	ret = hv_do_fast_hypercall16(HVCALL_SEND_IPI, ipi_arg.vector,
> +	status = hv_do_fast_hypercall16(HVCALL_SEND_IPI, ipi_arg.vector,
>  				     ipi_arg.cpu_mask);
> -	return ((ret == 0) ? true : false);
> +	return hv_result_success(status);
> 
>  do_ex_hypercall:
>  	return __send_ipi_mask_ex(mask, vector);
> @@ -195,6 +195,7 @@ static bool __send_ipi_mask(const struct cpumask *mask, int
> vector)
>  static bool __send_ipi_one(int cpu, int vector)
>  {
>  	int vp = hv_cpu_number_to_vp_number(cpu);
> +	u64 status;
> 
>  	trace_hyperv_send_ipi_one(cpu, vector);
> 
> @@ -207,7 +208,8 @@ static bool __send_ipi_one(int cpu, int vector)
>  	if (vp >= 64)
>  		return __send_ipi_mask_ex(cpumask_of(cpu), vector);
> 
> -	return !hv_do_fast_hypercall16(HVCALL_SEND_IPI, vector, BIT_ULL(vp));
> +	status = hv_do_fast_hypercall16(HVCALL_SEND_IPI, vector, BIT_ULL(vp));
> +	return hv_result_success(status);
>  }
> 
>  static void hv_send_ipi(int cpu, int vector)
> diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
> index b81047dec1da..a5b73584e2cc 100644
> --- a/arch/x86/hyperv/hv_init.c
> +++ b/arch/x86/hyperv/hv_init.c
> @@ -369,7 +369,7 @@ static void __init hv_get_partition_id(void)
>  	local_irq_save(flags);
>  	output_page = *this_cpu_ptr(hyperv_pcpu_output_arg);
>  	status = hv_do_hypercall(HVCALL_GET_PARTITION_ID, NULL, output_page);
> -	if ((status & HV_HYPERCALL_RESULT_MASK) != HV_STATUS_SUCCESS) {
> +	if (!hv_result_success(status)) {
>  		/* No point in proceeding if this failed */
>  		pr_err("Failed to get partition ID: %lld\n", status);
>  		BUG();
> diff --git a/arch/x86/hyperv/hv_proc.c b/arch/x86/hyperv/hv_proc.c
> index 60461e598239..f16234aef358 100644
> --- a/arch/x86/hyperv/hv_proc.c
> +++ b/arch/x86/hyperv/hv_proc.c
> @@ -93,10 +93,9 @@ int hv_call_deposit_pages(int node, u64 partition_id, u32
> num_pages)
>  	status = hv_do_rep_hypercall(HVCALL_DEPOSIT_MEMORY,
>  				     page_count, 0, input_page, NULL);
>  	local_irq_restore(flags);
> -
> -	if ((status & HV_HYPERCALL_RESULT_MASK) != HV_STATUS_SUCCESS) {
> +	if (!hv_result_success(status)) {
>  		pr_err("Failed to deposit pages: %lld\n", status);
> -		ret = status;
> +		ret = hv_result(status);
>  		goto err_free_allocations;
>  	}
> 
> @@ -122,7 +121,7 @@ int hv_call_add_logical_proc(int node, u32 lp_index, u32 apic_id)
>  	struct hv_add_logical_processor_out *output;
>  	u64 status;
>  	unsigned long flags;
> -	int ret = 0;
> +	int ret = HV_STATUS_SUCCESS;
>  	int pxm = node_to_pxm(node);
> 
>  	/*
> @@ -148,13 +147,11 @@ int hv_call_add_logical_proc(int node, u32 lp_index, u32 apic_id)
>  					 input, output);
>  		local_irq_restore(flags);
> 
> -		status &= HV_HYPERCALL_RESULT_MASK;
> -
> -		if (status != HV_STATUS_INSUFFICIENT_MEMORY) {
> -			if (status != HV_STATUS_SUCCESS) {
> +		if (hv_result(status) != HV_STATUS_INSUFFICIENT_MEMORY) {
> +			if (!hv_result_success(status)) {
>  				pr_err("%s: cpu %u apic ID %u, %lld\n", __func__,
>  				       lp_index, apic_id, status);
> -				ret = status;
> +				ret = hv_result(status);
>  			}
>  			break;
>  		}
> @@ -169,7 +166,7 @@ int hv_call_create_vp(int node, u64 partition_id, u32 vp_index, u32
> flags)
>  	struct hv_create_vp *input;
>  	u64 status;
>  	unsigned long irq_flags;
> -	int ret = 0;
> +	int ret = HV_STATUS_SUCCESS;
>  	int pxm = node_to_pxm(node);
> 
>  	/* Root VPs don't seem to need pages deposited */
> @@ -200,13 +197,11 @@ int hv_call_create_vp(int node, u64 partition_id, u32 vp_index,
> u32 flags)
>  		status = hv_do_hypercall(HVCALL_CREATE_VP, input, NULL);
>  		local_irq_restore(irq_flags);
> 
> -		status &= HV_HYPERCALL_RESULT_MASK;
> -
> -		if (status != HV_STATUS_INSUFFICIENT_MEMORY) {
> -			if (status != HV_STATUS_SUCCESS) {
> +		if (hv_result(status) != HV_STATUS_INSUFFICIENT_MEMORY) {
> +			if (!hv_result_success(status)) {
>  				pr_err("%s: vcpu %u, lp %u, %lld\n", __func__,
>  				       vp_index, flags, status);
> -				ret = status;
> +				ret = hv_result(status);
>  			}
>  			break;
>  		}
> diff --git a/arch/x86/hyperv/irqdomain.c b/arch/x86/hyperv/irqdomain.c
> index 4421a8d92e23..514fc64e23d5 100644
> --- a/arch/x86/hyperv/irqdomain.c
> +++ b/arch/x86/hyperv/irqdomain.c
> @@ -63,10 +63,10 @@ static int hv_map_interrupt(union hv_device_id device_id, bool
> level,
> 
>  	local_irq_restore(flags);
> 
> -	if ((status & HV_HYPERCALL_RESULT_MASK) != HV_STATUS_SUCCESS)
> +	if (!hv_result_success(status))
>  		pr_err("%s: hypercall failed, status %lld\n", __func__, status);
> 
> -	return status & HV_HYPERCALL_RESULT_MASK;
> +	return hv_result(status);
>  }
> 
>  static int hv_unmap_interrupt(u64 id, struct hv_interrupt_entry *old_entry)
> @@ -88,7 +88,7 @@ static int hv_unmap_interrupt(u64 id, struct hv_interrupt_entry
> *old_entry)
>  	status = hv_do_hypercall(HVCALL_UNMAP_DEVICE_INTERRUPT, input, NULL);
>  	local_irq_restore(flags);
> 
> -	return status & HV_HYPERCALL_RESULT_MASK;
> +	return hv_result(status);
>  }
> 
>  #ifdef CONFIG_PCI_MSI
> diff --git a/arch/x86/hyperv/mmu.c b/arch/x86/hyperv/mmu.c
> index 2c87350c1fb0..c0ba8874d9cb 100644
> --- a/arch/x86/hyperv/mmu.c
> +++ b/arch/x86/hyperv/mmu.c
> @@ -58,7 +58,7 @@ static void hyperv_flush_tlb_others(const struct cpumask *cpus,
>  	int cpu, vcpu, gva_n, max_gvas;
>  	struct hv_tlb_flush **flush_pcpu;
>  	struct hv_tlb_flush *flush;
> -	u64 status = U64_MAX;
> +	u64 status;
>  	unsigned long flags;
> 
>  	trace_hyperv_mmu_flush_tlb_others(cpus, info);
> @@ -161,7 +161,7 @@ static void hyperv_flush_tlb_others(const struct cpumask *cpus,
>  check_status:
>  	local_irq_restore(flags);
> 
> -	if (!(status & HV_HYPERCALL_RESULT_MASK))
> +	if (hv_result_success(status))
>  		return;
>  do_native:
>  	native_flush_tlb_others(cpus, info);
> @@ -176,7 +176,7 @@ static u64 hyperv_flush_tlb_others_ex(const struct cpumask *cpus,
>  	u64 status;
> 
>  	if (!(ms_hyperv.hints & HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED))
> -		return U64_MAX;
> +		return HV_STATUS_INVALID_PARAMETER;
> 
>  	flush_pcpu = (struct hv_tlb_flush_ex **)
>  		     this_cpu_ptr(hyperv_pcpu_input_arg);
> @@ -201,7 +201,7 @@ static u64 hyperv_flush_tlb_others_ex(const struct cpumask *cpus,
>  	flush->hv_vp_set.format = HV_GENERIC_SET_SPARSE_4K;
>  	nr_bank = cpumask_to_vpset(&(flush->hv_vp_set), cpus);
>  	if (nr_bank < 0)
> -		return U64_MAX;
> +		return HV_STATUS_INVALID_PARAMETER;
> 
>  	/*
>  	 * We can flush not more than max_gvas with one hypercall. Flush the
> diff --git a/arch/x86/hyperv/nested.c b/arch/x86/hyperv/nested.c
> index dd0a843f766d..5d70968c8538 100644
> --- a/arch/x86/hyperv/nested.c
> +++ b/arch/x86/hyperv/nested.c
> @@ -47,7 +47,7 @@ int hyperv_flush_guest_mapping(u64 as)
>  				 flush, NULL);
>  	local_irq_restore(flags);
> 
> -	if (!(status & HV_HYPERCALL_RESULT_MASK))
> +	if (hv_result_success(status))
>  		ret = 0;
> 
>  fault:
> @@ -92,7 +92,7 @@ int hyperv_flush_guest_mapping_range(u64 as,
>  {
>  	struct hv_guest_mapping_flush_list **flush_pcpu;
>  	struct hv_guest_mapping_flush_list *flush;
> -	u64 status = 0;
> +	u64 status;
>  	unsigned long flags;
>  	int ret = -ENOTSUPP;
>  	int gpa_n = 0;
> @@ -125,10 +125,10 @@ int hyperv_flush_guest_mapping_range(u64 as,
> 
>  	local_irq_restore(flags);
> 
> -	if (!(status & HV_HYPERCALL_RESULT_MASK))
> +	if (hv_result_success(status))
>  		ret = 0;
>  	else
> -		ret = status;
> +		ret = hv_result(status);
>  fault:
>  	trace_hyperv_nested_flush_guest_mapping_range(as, ret);
>  	return ret;
> diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
> index bfc98b490f07..759136f98e19 100644
> --- a/arch/x86/include/asm/mshyperv.h
> +++ b/arch/x86/include/asm/mshyperv.h
> @@ -9,6 +9,7 @@
>  #include <asm/hyperv-tlfs.h>
>  #include <asm/nospec-branch.h>
>  #include <asm/paravirt.h>
> +#include <asm/mshyperv.h>
> 
>  typedef int (*hyperv_fill_flush_list_func)(
>  		struct hv_guest_mapping_flush_list *flush,
> diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
> index f202ac7f4b3d..307fe26dd81a 100644
> --- a/drivers/hv/hv.c
> +++ b/drivers/hv/hv.c
> @@ -68,7 +68,7 @@ int hv_post_message(union hv_connection_id connection_id,
>  	 */
>  	put_cpu_ptr(hv_cpu);
> 
> -	return status & 0xFFFF;
> +	return hv_result(status);
>  }
> 
>  int hv_synic_alloc(void)
> diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
> index 27a17a1e4a7c..aa278005dea2 100644
> --- a/drivers/pci/controller/pci-hyperv.c
> +++ b/drivers/pci/controller/pci-hyperv.c
> @@ -1292,7 +1292,7 @@ static void hv_irq_unmask(struct irq_data *data)
>  	 * resumes, hv_pci_restore_msi_state() is able to correctly restore
>  	 * the interrupt with the correct affinity.
>  	 */
> -	if (res && hbus->state != hv_pcibus_removing)
> +	if (!hv_result_success(res) && hbus->state != hv_pcibus_removing)
>  		dev_err(&hbus->hdev->device,
>  			"%s() failed: %#llx", __func__, res);
> 
> diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
> index a5246a6ea02d..27d85d675e9a 100644
> --- a/include/asm-generic/mshyperv.h
> +++ b/include/asm-generic/mshyperv.h
> @@ -41,6 +41,24 @@ extern struct ms_hyperv_info ms_hyperv;
>  extern u64 hv_do_hypercall(u64 control, void *inputaddr, void *outputaddr);
>  extern u64 hv_do_fast_hypercall8(u16 control, u64 input8);
> 
> +/* Helper functions that provide a consistent pattern for checking Hyper-V hypercall
> status. */
> +static inline int hv_result(u64 status)
> +{
> +	return status & HV_HYPERCALL_RESULT_MASK;
> +}
> +
> +static inline bool hv_result_success(u64 status)
> +{
> +	return hv_result(status) == HV_STATUS_SUCCESS;
> +}
> +
> +static inline unsigned int hv_repcomp(u64 status)
> +{
> +	/* Bits [43:32] of status have 'Reps completed' data. */
> +	return (status & HV_HYPERCALL_REP_COMP_MASK) >>
> +			 HV_HYPERCALL_REP_COMP_OFFSET;
> +}
> +
>  /*
>   * Rep hypercalls. Callers of this functions are supposed to ensure that
>   * rep_count and varhead_size comply with Hyper-V hypercall definition.
> @@ -57,12 +75,10 @@ static inline u64 hv_do_rep_hypercall(u16 code, u16 rep_count, u16
> varhead_size,
> 
>  	do {
>  		status = hv_do_hypercall(control, input, output);
> -		if ((status & HV_HYPERCALL_RESULT_MASK) != HV_STATUS_SUCCESS)
> +		if (!hv_result_success(status))
>  			return status;
> 
> -		/* Bits 32-43 of status have 'Reps completed' data. */
> -		rep_comp = (status & HV_HYPERCALL_REP_COMP_MASK) >>
> -			HV_HYPERCALL_REP_COMP_OFFSET;
> +		rep_comp = hv_repcomp(status);
> 
>  		control &= ~HV_HYPERCALL_REP_START_MASK;
>  		control |= (u64)rep_comp << HV_HYPERCALL_REP_START_OFFSET;
> @@ -87,7 +103,6 @@ static inline  __u64 generate_guest_id(__u64 d_info1, __u64
> kernel_version,
>  	return guest_id;
>  }
> 
> -
>  /* Free the message slot and signal end-of-message if required */
>  static inline void vmbus_signal_eom(struct hv_message *msg, u32 old_msg_type)
>  {
> --
> 2.17.1