diff mbox series

[RFC,v2,13/26] x86/sgx: Add helpers to expose ECREATE and EINIT to KVM

Message ID e9a350fac5b18ca69496d07fe25a7a2408d1a73a.1610935432.git.kai.huang@intel.com (mailing list archive)
State New, archived
Headers show
Series KVM SGX virtualization support | expand

Commit Message

Kai Huang Jan. 18, 2021, 3:28 a.m. UTC 
From: Sean Christopherson <sean.j.christopherson@intel.com>

The bare-metal kernel must intercept ECREATE to be able to impose policies
on guests.  When it does this, the bare-metal kernel runs ECREATE against
the userspace mapping of the virtualized EPC.

Provide wrappers around __ecreate() and __einit() to hide the ugliness
of overloading the ENCLS return value to encode multiple error formats
in a single int.  KVM will trap-and-execute ECREATE and EINIT as part
of SGX virtualization, and on an exception, KVM needs the trapnr so that
it can inject the correct fault into the guest.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
 [Kai: Use sgx_update_lepubkeyhash() to update pubkey hash MSRs.]
Signed-off-by: Kai Huang <kai.huang@intel.com>
---
v1->v2:

 - Refined commit msg based on Dave's comment.
 - Added comment to explain why to use __uaccess_xxx().
---
 arch/x86/include/asm/sgx.h     | 16 +++++++++
 arch/x86/kernel/cpu/sgx/virt.c | 61 ++++++++++++++++++++++++++++++++++
 2 files changed, 77 insertions(+)
 create mode 100644 arch/x86/include/asm/sgx.h

Comments

Jarkko Sakkinen Jan. 20, 2021, 12:04 p.m. UTC | #1 
On Mon, Jan 18, 2021 at 04:28:06PM +1300, Kai Huang wrote:
> From: Sean Christopherson <sean.j.christopherson@intel.com>
> 
> The bare-metal kernel must intercept ECREATE to be able to impose policies
> on guests.  When it does this, the bare-metal kernel runs ECREATE against
> the userspace mapping of the virtualized EPC.
> 
> Provide wrappers around __ecreate() and __einit() to hide the ugliness
> of overloading the ENCLS return value to encode multiple error formats
> in a single int.  KVM will trap-and-execute ECREATE and EINIT as part
> of SGX virtualization, and on an exception, KVM needs the trapnr so that
> it can inject the correct fault into the guest.
> 
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
>  [Kai: Use sgx_update_lepubkeyhash() to update pubkey hash MSRs.]

If you have to go to this, please instead use co-developed-by.

> Signed-off-by: Kai Huang <kai.huang@intel.com>
> ---
> v1->v2:
> 
>  - Refined commit msg based on Dave's comment.
>  - Added comment to explain why to use __uaccess_xxx().
> ---
>  arch/x86/include/asm/sgx.h     | 16 +++++++++
>  arch/x86/kernel/cpu/sgx/virt.c | 61 ++++++++++++++++++++++++++++++++++
>  2 files changed, 77 insertions(+)
>  create mode 100644 arch/x86/include/asm/sgx.h
> 
> diff --git a/arch/x86/include/asm/sgx.h b/arch/x86/include/asm/sgx.h
> new file mode 100644
> index 000000000000..0d643b985085
> --- /dev/null
> +++ b/arch/x86/include/asm/sgx.h
> @@ -0,0 +1,16 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _ASM_X86_SGX_H
> +#define _ASM_X86_SGX_H
> +
> +#include <linux/types.h>
> +
> +#ifdef CONFIG_X86_SGX_VIRTUALIZATION
> +struct sgx_pageinfo;
> +
> +int sgx_virt_ecreate(struct sgx_pageinfo *pageinfo, void __user *secs,
> +		     int *trapnr);
> +int sgx_virt_einit(void __user *sigstruct, void __user *token,
> +		   void __user *secs, u64 *lepubkeyhash, int *trapnr);
> +#endif
> +
> +#endif /* _ASM_X86_SGX_H */
> diff --git a/arch/x86/kernel/cpu/sgx/virt.c b/arch/x86/kernel/cpu/sgx/virt.c
> index 1e8620f20651..97f02e5235ca 100644
> --- a/arch/x86/kernel/cpu/sgx/virt.c
> +++ b/arch/x86/kernel/cpu/sgx/virt.c
> @@ -253,3 +253,64 @@ int __init sgx_virt_epc_init(void)
>  
>  	return misc_register(&sgx_virt_epc_dev);
>  }
> +
> +int sgx_virt_ecreate(struct sgx_pageinfo *pageinfo, void __user *secs,
> +		     int *trapnr)
> +{
> +	int ret;
> +
> +	/*
> +	 * @secs is userspace address, and it's not guaranteed @secs points at
> +	 * an actual EPC page. It's also possible to generate a kernel mapping
> +	 * to physical EPC page by resolving PFN but using __uaccess_xx() is
> +	 * simpler.
> +	 */
> +	__uaccess_begin();
> +	ret = __ecreate(pageinfo, (void *)secs);
> +	__uaccess_end();
> +
> +	if (encls_faulted(ret)) {
> +		*trapnr = ENCLS_TRAPNR(ret);
> +		return -EFAULT;
> +	}
> +
> +	/* ECREATE doesn't return an error code, it faults or succeeds. */
> +	WARN_ON_ONCE(ret);
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(sgx_virt_ecreate);
> +
> +static int __sgx_virt_einit(void __user *sigstruct, void __user *token,
> +			    void __user *secs)
> +{
> +	int ret;
> +
> +	__uaccess_begin();
> +	ret =  __einit((void *)sigstruct, (void *)token, (void *)secs);
> +	__uaccess_end();
> +	return ret;
> +}
> +
> +int sgx_virt_einit(void __user *sigstruct, void __user *token,
> +		   void __user *secs, u64 *lepubkeyhash, int *trapnr)

kdoc missing.

> +{
> +	int ret;
> +
> +	if (!boot_cpu_has(X86_FEATURE_SGX_LC)) {
> +		ret = __sgx_virt_einit(sigstruct, token, secs);
> +	} else {
> +		preempt_disable();
> +
> +		sgx_update_lepubkeyhash(lepubkeyhash);
> +
> +		ret = __sgx_virt_einit(sigstruct, token, secs);
> +		preempt_enable();
> +	}
> +
> +	if (encls_faulted(ret)) {
> +		*trapnr = ENCLS_TRAPNR(ret);
> +		return -EFAULT;
> +	}
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(sgx_virt_einit);
> -- 
> 2.29.2
> 
> 

/Jarkko
Kai Huang Jan. 20, 2021, 11:29 p.m. UTC | #2 
On Wed, 20 Jan 2021 14:04:36 +0200 Jarkko Sakkinen wrote:
> On Mon, Jan 18, 2021 at 04:28:06PM +1300, Kai Huang wrote:
> > From: Sean Christopherson <sean.j.christopherson@intel.com>
> > 
> > The bare-metal kernel must intercept ECREATE to be able to impose policies
> > on guests.  When it does this, the bare-metal kernel runs ECREATE against
> > the userspace mapping of the virtualized EPC.
> > 
> > Provide wrappers around __ecreate() and __einit() to hide the ugliness
> > of overloading the ENCLS return value to encode multiple error formats
> > in a single int.  KVM will trap-and-execute ECREATE and EINIT as part
> > of SGX virtualization, and on an exception, KVM needs the trapnr so that
> > it can inject the correct fault into the guest.
> > 
> > Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> >  [Kai: Use sgx_update_lepubkeyhash() to update pubkey hash MSRs.]
> 
> If you have to go to this, please instead use co-developed-by.

I'll remove it. I don't want to use co-developed-by here.

> 
> > Signed-off-by: Kai Huang <kai.huang@intel.com>
> > ---
> > v1->v2:
> > 
> >  - Refined commit msg based on Dave's comment.
> >  - Added comment to explain why to use __uaccess_xxx().
> > ---
> >  arch/x86/include/asm/sgx.h     | 16 +++++++++
> >  arch/x86/kernel/cpu/sgx/virt.c | 61 ++++++++++++++++++++++++++++++++++
> >  2 files changed, 77 insertions(+)
> >  create mode 100644 arch/x86/include/asm/sgx.h
> > 
> > diff --git a/arch/x86/include/asm/sgx.h b/arch/x86/include/asm/sgx.h
> > new file mode 100644
> > index 000000000000..0d643b985085
> > --- /dev/null
> > +++ b/arch/x86/include/asm/sgx.h
> > @@ -0,0 +1,16 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +#ifndef _ASM_X86_SGX_H
> > +#define _ASM_X86_SGX_H
> > +
> > +#include <linux/types.h>
> > +
> > +#ifdef CONFIG_X86_SGX_VIRTUALIZATION
> > +struct sgx_pageinfo;
> > +
> > +int sgx_virt_ecreate(struct sgx_pageinfo *pageinfo, void __user *secs,
> > +		     int *trapnr);
> > +int sgx_virt_einit(void __user *sigstruct, void __user *token,
> > +		   void __user *secs, u64 *lepubkeyhash, int *trapnr);
> > +#endif
> > +
> > +#endif /* _ASM_X86_SGX_H */
> > diff --git a/arch/x86/kernel/cpu/sgx/virt.c b/arch/x86/kernel/cpu/sgx/virt.c
> > index 1e8620f20651..97f02e5235ca 100644
> > --- a/arch/x86/kernel/cpu/sgx/virt.c
> > +++ b/arch/x86/kernel/cpu/sgx/virt.c
> > @@ -253,3 +253,64 @@ int __init sgx_virt_epc_init(void)
> >  
> >  	return misc_register(&sgx_virt_epc_dev);
> >  }
> > +
> > +int sgx_virt_ecreate(struct sgx_pageinfo *pageinfo, void __user *secs,
> > +		     int *trapnr)
> > +{
> > +	int ret;
> > +
> > +	/*
> > +	 * @secs is userspace address, and it's not guaranteed @secs points at
> > +	 * an actual EPC page. It's also possible to generate a kernel mapping
> > +	 * to physical EPC page by resolving PFN but using __uaccess_xx() is
> > +	 * simpler.
> > +	 */
> > +	__uaccess_begin();
> > +	ret = __ecreate(pageinfo, (void *)secs);
> > +	__uaccess_end();
> > +
> > +	if (encls_faulted(ret)) {
> > +		*trapnr = ENCLS_TRAPNR(ret);
> > +		return -EFAULT;
> > +	}
> > +
> > +	/* ECREATE doesn't return an error code, it faults or succeeds. */
> > +	WARN_ON_ONCE(ret);
> > +	return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(sgx_virt_ecreate);
> > +
> > +static int __sgx_virt_einit(void __user *sigstruct, void __user *token,
> > +			    void __user *secs)
> > +{
> > +	int ret;
> > +
> > +	__uaccess_begin();
> > +	ret =  __einit((void *)sigstruct, (void *)token, (void *)secs);
> > +	__uaccess_end();
> > +	return ret;
> > +}
> > +
> > +int sgx_virt_einit(void __user *sigstruct, void __user *token,
> > +		   void __user *secs, u64 *lepubkeyhash, int *trapnr)
> 
> kdoc missing.

OK. Will add for both sgx_virt_create() and sgx_virt_init().

> 
> > +{
> > +	int ret;
> > +
> > +	if (!boot_cpu_has(X86_FEATURE_SGX_LC)) {
> > +		ret = __sgx_virt_einit(sigstruct, token, secs);
> > +	} else {
> > +		preempt_disable();
> > +
> > +		sgx_update_lepubkeyhash(lepubkeyhash);
> > +
> > +		ret = __sgx_virt_einit(sigstruct, token, secs);
> > +		preempt_enable();
> > +	}
> > +
> > +	if (encls_faulted(ret)) {
> > +		*trapnr = ENCLS_TRAPNR(ret);
> > +		return -EFAULT;
> > +	}
> > +	return ret;
> > +}
> > +EXPORT_SYMBOL_GPL(sgx_virt_einit);
> > -- 
> > 2.29.2
> > 
> > 
> 
> /Jarkko
diff mbox series

Patch

diff --git a/arch/x86/include/asm/sgx.h b/arch/x86/include/asm/sgx.h
new file mode 100644
index 000000000000..0d643b985085
--- /dev/null
+++ b/arch/x86/include/asm/sgx.h
@@ -0,0 +1,16 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_X86_SGX_H
+#define _ASM_X86_SGX_H
+
+#include <linux/types.h>
+
+#ifdef CONFIG_X86_SGX_VIRTUALIZATION
+struct sgx_pageinfo;
+
+int sgx_virt_ecreate(struct sgx_pageinfo *pageinfo, void __user *secs,
+		     int *trapnr);
+int sgx_virt_einit(void __user *sigstruct, void __user *token,
+		   void __user *secs, u64 *lepubkeyhash, int *trapnr);
+#endif
+
+#endif /* _ASM_X86_SGX_H */
diff --git a/arch/x86/kernel/cpu/sgx/virt.c b/arch/x86/kernel/cpu/sgx/virt.c
index 1e8620f20651..97f02e5235ca 100644
--- a/arch/x86/kernel/cpu/sgx/virt.c
+++ b/arch/x86/kernel/cpu/sgx/virt.c
@@ -253,3 +253,64 @@  int __init sgx_virt_epc_init(void)
 
 	return misc_register(&sgx_virt_epc_dev);
 }
+
+int sgx_virt_ecreate(struct sgx_pageinfo *pageinfo, void __user *secs,
+		     int *trapnr)
+{
+	int ret;
+
+	/*
+	 * @secs is userspace address, and it's not guaranteed @secs points at
+	 * an actual EPC page. It's also possible to generate a kernel mapping
+	 * to physical EPC page by resolving PFN but using __uaccess_xx() is
+	 * simpler.
+	 */
+	__uaccess_begin();
+	ret = __ecreate(pageinfo, (void *)secs);
+	__uaccess_end();
+
+	if (encls_faulted(ret)) {
+		*trapnr = ENCLS_TRAPNR(ret);
+		return -EFAULT;
+	}
+
+	/* ECREATE doesn't return an error code, it faults or succeeds. */
+	WARN_ON_ONCE(ret);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(sgx_virt_ecreate);
+
+static int __sgx_virt_einit(void __user *sigstruct, void __user *token,
+			    void __user *secs)
+{
+	int ret;
+
+	__uaccess_begin();
+	ret =  __einit((void *)sigstruct, (void *)token, (void *)secs);
+	__uaccess_end();
+	return ret;
+}
+
+int sgx_virt_einit(void __user *sigstruct, void __user *token,
+		   void __user *secs, u64 *lepubkeyhash, int *trapnr)
+{
+	int ret;
+
+	if (!boot_cpu_has(X86_FEATURE_SGX_LC)) {
+		ret = __sgx_virt_einit(sigstruct, token, secs);
+	} else {
+		preempt_disable();
+
+		sgx_update_lepubkeyhash(lepubkeyhash);
+
+		ret = __sgx_virt_einit(sigstruct, token, secs);
+		preempt_enable();
+	}
+
+	if (encls_faulted(ret)) {
+		*trapnr = ENCLS_TRAPNR(ret);
+		return -EFAULT;
+	}
+	return ret;
+}
+EXPORT_SYMBOL_GPL(sgx_virt_einit);