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Message-ID: <5bb525c3-cc6d-f526-aeb8-4b7ef1a3eb55@linux.microsoft.com>
Date:   Mon, 9 Jan 2023 09:03:36 -0800
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Subject: Re: [PATCH v10 2/5] Drivers: hv: Setup synic registers in case of
 nested root partition
To:     Jinank Jain <jinankjain@linux.microsoft.com>,
        jinankjain@microsoft.com
Cc:     kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org,
        decui@microsoft.com, tglx@linutronix.de, mingo@redhat.com,
        bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org,
        hpa@zytor.com, arnd@arndb.de, peterz@infradead.org,
        jpoimboe@kernel.org, seanjc@google.com,
        kirill.shutemov@linux.intel.com, ak@linux.intel.com,
        sathyanarayanan.kuppuswamy@linux.intel.com,
        linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arch@vger.kernel.org, anrayabh@linux.microsoft.com,
        mikelley@microsoft.com
References: <cover.1672639707.git.jinankjain@linux.microsoft.com>
 <cb951fb1ad6814996fc54f4a255c5841a20a151f.1672639707.git.jinankjain@linux.microsoft.com>
Content-Language: en-US
From:   Nuno Das Neves <nunodasneves@linux.microsoft.com>
In-Reply-To: <cb951fb1ad6814996fc54f4a255c5841a20a151f.1672639707.git.jinankjain@linux.microsoft.com>
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Precedence: bulk

On 1/1/2023 11:12 PM, Jinank Jain wrote:
> Child partitions are free to allocate SynIC message and event page but in
> case of root partition it must use the pages allocated by Microsoft
> Hypervisor (MSHV). Base address for these pages can be found using
> synthetic MSRs exposed by MSHV. There is a slight difference in those MSRs
> for nested vs non-nested root partition.
> 
> Signed-off-by: Jinank Jain <jinankjain@linux.microsoft.com>
> ---
>  arch/x86/include/asm/hyperv-tlfs.h | 11 +++++
>  arch/x86/include/asm/mshyperv.h    | 30 +++-----------
>  arch/x86/kernel/cpu/mshyperv.c     | 65 ++++++++++++++++++++++++++++++
>  drivers/hv/hv.c                    | 18 +++++----
>  4 files changed, 93 insertions(+), 31 deletions(-)
> 
> diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
> index 58c03d18c235..b5019becb618 100644
> --- a/arch/x86/include/asm/hyperv-tlfs.h
> +++ b/arch/x86/include/asm/hyperv-tlfs.h
> @@ -225,6 +225,17 @@ enum hv_isolation_type {
>  #define HV_REGISTER_SINT14			0x4000009E
>  #define HV_REGISTER_SINT15			0x4000009F
>  
> +/*
> + * Define synthetic interrupt controller model specific registers for
> + * nested hypervisor.
> + */
> +#define HV_REGISTER_NESTED_SCONTROL            0x40001080
> +#define HV_REGISTER_NESTED_SVERSION            0x40001081
> +#define HV_REGISTER_NESTED_SIEFP               0x40001082
> +#define HV_REGISTER_NESTED_SIMP                0x40001083
> +#define HV_REGISTER_NESTED_EOM                 0x40001084
> +#define HV_REGISTER_NESTED_SINT0               0x40001090
> +
>  /*
>   * Synthetic Timer MSRs. Four timers per vcpu.
>   */
> diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
> index 61f0c206bff0..c38e4c66a3ac 100644
> --- a/arch/x86/include/asm/mshyperv.h
> +++ b/arch/x86/include/asm/mshyperv.h
> @@ -198,30 +198,10 @@ static inline bool hv_is_synic_reg(unsigned int reg)
>  	return false;
>  }
>  
> -static inline u64 hv_get_register(unsigned int reg)
> -{
> -	u64 value;
> -
> -	if (hv_is_synic_reg(reg) && hv_isolation_type_snp())
> -		hv_ghcb_msr_read(reg, &value);
> -	else
> -		rdmsrl(reg, value);
> -	return value;
> -}
> -
> -static inline void hv_set_register(unsigned int reg, u64 value)
> -{
> -	if (hv_is_synic_reg(reg) && hv_isolation_type_snp()) {
> -		hv_ghcb_msr_write(reg, value);
> -
> -		/* Write proxy bit via wrmsl instruction */
> -		if (reg >= HV_REGISTER_SINT0 &&
> -		    reg <= HV_REGISTER_SINT15)
> -			wrmsrl(reg, value | 1 << 20);
> -	} else {
> -		wrmsrl(reg, value);
> -	}
> -}
> +u64 hv_get_register(unsigned int reg);
> +void hv_set_register(unsigned int reg, u64 value);
> +u64 hv_get_non_nested_register(unsigned int reg);
> +void hv_set_non_nested_register(unsigned int reg, u64 value);
>  
>  #else /* CONFIG_HYPERV */
>  static inline void hyperv_init(void) {}
> @@ -241,6 +221,8 @@ static inline int hyperv_flush_guest_mapping_range(u64 as,
>  }
>  static inline void hv_set_register(unsigned int reg, u64 value) { }
>  static inline u64 hv_get_register(unsigned int reg) { return 0; }
> +static inline void hv_set_non_nested_register(unsigned int reg, u64 value) { }
> +static inline u64 hv_get_non_nested_register(unsigned int reg) { return 0; }
>  static inline int hv_set_mem_host_visibility(unsigned long addr, int numpages,
>  					     bool visible)
>  {
> diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
> index f9b78d4829e3..938fc82edf05 100644
> --- a/arch/x86/kernel/cpu/mshyperv.c
> +++ b/arch/x86/kernel/cpu/mshyperv.c
> @@ -41,7 +41,72 @@ bool hv_root_partition;
>  bool hv_nested;
>  struct ms_hyperv_info ms_hyperv;
>  
> +static inline unsigned int hv_get_nested_reg(unsigned int reg)
> +{
> +	switch (reg) {
> +	case HV_REGISTER_SIMP:
> +		return HV_REGISTER_NESTED_SIMP;
> +	case HV_REGISTER_SIEFP:
> +		return HV_REGISTER_NESTED_SIEFP;
> +	case HV_REGISTER_SVERSION:
> +		return HV_REGISTER_NESTED_SVERSION;
> +	case HV_REGISTER_SCONTROL:
> +		return HV_REGISTER_NESTED_SCONTROL;
> +	case HV_REGISTER_SINT0:
> +		return HV_REGISTER_NESTED_SINT0;
> +	case HV_REGISTER_EOM:
> +		return HV_REGISTER_NESTED_EOM;
> +	default:
> +		return reg;
> +	}
> +}
> +
>  #if IS_ENABLED(CONFIG_HYPERV)
> +u64 hv_get_non_nested_register(unsigned int reg)
> +{
> +	u64 value;
> +
> +	if (hv_is_synic_reg(reg) && hv_isolation_type_snp())
> +		hv_ghcb_msr_read(reg, &value);
> +	else
> +		rdmsrl(reg, value);
> +	return value;
> +}
> +EXPORT_SYMBOL_GPL(hv_get_non_nested_register);
> +
> +void hv_set_non_nested_register(unsigned int reg, u64 value)
> +{
> +	if (hv_is_synic_reg(reg) && hv_isolation_type_snp()) {
> +		hv_ghcb_msr_write(reg, value);
> +
> +		/* Write proxy bit via wrmsl instruction */
> +		if (reg >= HV_REGISTER_SINT0 &&
> +		    reg <= HV_REGISTER_SINT15)
> +			wrmsrl(reg, value | 1 << 20);
> +	} else {
> +		wrmsrl(reg, value);
> +	}
> +}
> +EXPORT_SYMBOL_GPL(hv_set_non_nested_register);
> +
> +u64 hv_get_register(unsigned int reg)
> +{
> +	if (hv_nested)
> +		reg = hv_get_nested_reg(reg);
> +
> +	return hv_get_non_nested_register(reg);
> +}
> +EXPORT_SYMBOL_GPL(hv_get_register);
> +
> +void hv_set_register(unsigned int reg, u64 value)
> +{
> +	if (hv_nested)
> +		reg = hv_get_nested_reg(reg);
> +
> +	hv_set_non_nested_register(reg, value);
> +}
> +EXPORT_SYMBOL_GPL(hv_set_register);
> +
>  static void (*vmbus_handler)(void);
>  static void (*hv_stimer0_handler)(void);
>  static void (*hv_kexec_handler)(void);
> diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
> index 4d6480d57546..8b0dd8e5244d 100644
> --- a/drivers/hv/hv.c
> +++ b/drivers/hv/hv.c
> @@ -147,7 +147,7 @@ int hv_synic_alloc(void)
>  		 * Synic message and event pages are allocated by paravisor.
>  		 * Skip these pages allocation here.
>  		 */
> -		if (!hv_isolation_type_snp()) {
> +		if (!hv_isolation_type_snp() && !hv_root_partition) {
>  			hv_cpu->synic_message_page =
>  				(void *)get_zeroed_page(GFP_ATOMIC);
>  			if (hv_cpu->synic_message_page == NULL) {
> @@ -216,7 +216,7 @@ void hv_synic_enable_regs(unsigned int cpu)
>  	simp.as_uint64 = hv_get_register(HV_REGISTER_SIMP);
>  	simp.simp_enabled = 1;
>  
> -	if (hv_isolation_type_snp()) {
> +	if (hv_isolation_type_snp() || hv_root_partition) {
>  		hv_cpu->synic_message_page
>  			= memremap(simp.base_simp_gpa << HV_HYP_PAGE_SHIFT,
>  				   HV_HYP_PAGE_SIZE, MEMREMAP_WB);
> @@ -233,7 +233,7 @@ void hv_synic_enable_regs(unsigned int cpu)
>  	siefp.as_uint64 = hv_get_register(HV_REGISTER_SIEFP);
>  	siefp.siefp_enabled = 1;
>  
> -	if (hv_isolation_type_snp()) {
> +	if (hv_isolation_type_snp() || hv_root_partition) {
>  		hv_cpu->synic_event_page =
>  			memremap(siefp.base_siefp_gpa << HV_HYP_PAGE_SHIFT,
>  				 HV_HYP_PAGE_SIZE, MEMREMAP_WB);
> @@ -315,20 +315,24 @@ void hv_synic_disable_regs(unsigned int cpu)
>  	 * addresses.
>  	 */
>  	simp.simp_enabled = 0;
> -	if (hv_isolation_type_snp())
> +	if (hv_isolation_type_snp() || hv_root_partition) {
>  		memunmap(hv_cpu->synic_message_page);
> -	else
> +		hv_cpu->synic_message_page = NULL;
> +	} else {
>  		simp.base_simp_gpa = 0;
> +	}
>  
>  	hv_set_register(HV_REGISTER_SIMP, simp.as_uint64);
>  
>  	siefp.as_uint64 = hv_get_register(HV_REGISTER_SIEFP);
>  	siefp.siefp_enabled = 0;
>  
> -	if (hv_isolation_type_snp())
> +	if (hv_isolation_type_snp() || hv_root_partition) {
>  		memunmap(hv_cpu->synic_event_page);
> -	else
> +		hv_cpu->synic_event_page = NULL;
> +	} else {
>  		siefp.base_siefp_gpa = 0;
> +	}
>  
>  	hv_set_register(HV_REGISTER_SIEFP, siefp.as_uint64);
>  

Reviewed-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>