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[v5,1/3] x86/sgx: Repurpose the owner field as the virtual address of virtual EPC page

Message ID 20220622093705.2891642-2-zhiquan1.li@intel.com (mailing list archive)
State New, archived
Headers show
Series x86/sgx: fine grained SGX MCA behavior | expand

Commit Message

Zhiquan Li June 22, 2022, 9:37 a.m. UTC 
When a page triggers a machine check, it only reports the
physical address of EPC page. But in order to inject #MC into
hypervisor, the virtual address is required. Then repurpose the
"owner" field as the virtual address of the virtual EPC page so that
arch_memory_failure() can easily retrieve it.

Add a new EPC page flag - SGX_EPC_PAGE_KVM_GUEST to interpret the
meaning of the field.

Co-developed-by: Cathy Zhang <cathy.zhang@intel.com>
Signed-off-by: Cathy Zhang <cathy.zhang@intel.com>
Signed-off-by: Zhiquan Li <zhiquan1.li@intel.com>
Acked-by: Kai Huang <kai.huang@intel.com>

---
Changes since V4:
- Add Co-developed-by and Signed-off-by from Cathy Zhang, as she had
  fully discussed the flag name with Jarkko.
  Link: https://lore.kernel.org/all/df92395ade424401ac3c6322de568720@intel.com/
- Add Acked-by from Kai Huang
  Link: https://lore.kernel.org/linux-sgx/0676cd4e-d94b-e904-81ae-ca1c05d37070@intel.com/T/#mccfb11df30698dbd060f2b6f06383cda7f154ef3

Changes since V3:
- Take the definition of EPC page flag SGX_EPC_PAGE_KVM_GUEST from
  Cathy Zhang's third patch of SGX rebootless recovery patch set but
  discard irrelevant portion, since it might need some time to
  re-forge and these are two different features.
  Link: https://lore.kernel.org/linux-sgx/41704e5d4c03b49fcda12e695595211d950cfb08.camel@kernel.org/T/#m9782d23496cacecb7da07a67daa79f4b322ae170

Changes since V2:
- Rework the patch suggested by Jarkko.
- Remove struct sgx_vepc_page and relevant code.
- Remove new EPC page flag SGX_EPC_PAGE_IS_VEPC definition as it is
  duplicated to SGX_EPC_PAGE_KVM_GUEST.
  Link: https://lore.kernel.org/linux-sgx/eb95b32ecf3d44a695610cf7f2816785@intel.com/T/#u

Changes since V1:
- Add documentation suggested by Jarkko.
---
 arch/x86/kernel/cpu/sgx/sgx.h  | 2 ++
 arch/x86/kernel/cpu/sgx/virt.c | 4 +++-
 2 files changed, 5 insertions(+), 1 deletion(-)

Comments

Dave Hansen July 21, 2022, 4:42 p.m. UTC | #1 
On 6/22/22 02:37, Zhiquan Li wrote:
> diff --git a/arch/x86/kernel/cpu/sgx/virt.c b/arch/x86/kernel/cpu/sgx/virt.c
> index 6a77a14eee38..776ae5c1c032 100644
> --- a/arch/x86/kernel/cpu/sgx/virt.c
> +++ b/arch/x86/kernel/cpu/sgx/virt.c
> @@ -46,10 +46,12 @@ static int __sgx_vepc_fault(struct sgx_vepc *vepc,
>  	if (epc_page)
>  		return 0;
>  
> -	epc_page = sgx_alloc_epc_page(vepc, false);
> +	epc_page = sgx_alloc_epc_page((void *)addr, false);
>  	if (IS_ERR(epc_page))
>  		return PTR_ERR(epc_page);

Was the 'vepc' value simply unused before?
Huang, Kai July 21, 2022, 11:27 p.m. UTC | #2 
On Thu, 2022-07-21 at 09:42 -0700, Dave Hansen wrote:
> On 6/22/22 02:37, Zhiquan Li wrote:
> > diff --git a/arch/x86/kernel/cpu/sgx/virt.c b/arch/x86/kernel/cpu/sgx/virt.c
> > index 6a77a14eee38..776ae5c1c032 100644
> > --- a/arch/x86/kernel/cpu/sgx/virt.c
> > +++ b/arch/x86/kernel/cpu/sgx/virt.c
> > @@ -46,10 +46,12 @@ static int __sgx_vepc_fault(struct sgx_vepc *vepc,
> >  	if (epc_page)
> >  		return 0;
> >  
> > -	epc_page = sgx_alloc_epc_page(vepc, false);
> > +	epc_page = sgx_alloc_epc_page((void *)addr, false);
> >  	if (IS_ERR(epc_page))
> >  		return PTR_ERR(epc_page);
> 
> Was the 'vepc' value simply unused before?

Yes for EPC page assigned to KVM guest it was unused before this series.
diff mbox series

Patch

diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
index 0f17def9fe6f..b43582da1bcf 100644
--- a/arch/x86/kernel/cpu/sgx/sgx.h
+++ b/arch/x86/kernel/cpu/sgx/sgx.h
@@ -28,6 +28,8 @@ 
 
 /* Pages on free list */
 #define SGX_EPC_PAGE_IS_FREE		BIT(1)
+/* Pages allocated for KVM guest */
+#define SGX_EPC_PAGE_KVM_GUEST		BIT(2)
 
 struct sgx_epc_page {
 	unsigned int section;
diff --git a/arch/x86/kernel/cpu/sgx/virt.c b/arch/x86/kernel/cpu/sgx/virt.c
index 6a77a14eee38..776ae5c1c032 100644
--- a/arch/x86/kernel/cpu/sgx/virt.c
+++ b/arch/x86/kernel/cpu/sgx/virt.c
@@ -46,10 +46,12 @@  static int __sgx_vepc_fault(struct sgx_vepc *vepc,
 	if (epc_page)
 		return 0;
 
-	epc_page = sgx_alloc_epc_page(vepc, false);
+	epc_page = sgx_alloc_epc_page((void *)addr, false);
 	if (IS_ERR(epc_page))
 		return PTR_ERR(epc_page);
 
+	epc_page->flags |= SGX_EPC_PAGE_KVM_GUEST;
+
 	ret = xa_err(xa_store(&vepc->page_array, index, epc_page, GFP_KERNEL));
 	if (ret)
 		goto err_free;