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Subject[PATCH v4 06/16] powerpc: Introduce the MSR_S bit
Date
From: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>

Protected Execution Facility (PEF) is an architectural change for
POWER 9 that enables Secure Virtual Machines (SVMs). When enabled,
PEF adds a new higher privileged mode, called Ultravisor mode, to
POWER architecture.

The hardware changes include the following:

* There is a new bit in the MSR that determines whether the current
process is running in secure mode, MSR(S) bit 41. MSR(S)=1, process
is in secure mode, MSR(s)=0 process is in normal mode.

* The MSR(S) bit can only be set by the Ultravisor.

* HRFID cannot be used to set the MSR(S) bit. If the hypervisor needs
to return to a SVM it must use an ultracall. It can determine if
the VM it is returning to is secure.

* The privilege of a process is now determined by three MSR bits,
MSR(S, HV, PR). In each of the tables below the modes are listed
from least privilege to highest privilege. The higher privilege
modes can access all the resources of the lower privilege modes.

**Secure Mode MSR Settings**

+---+---+---+---------------+
| S | HV| PR|Privilege |
+===+===+===+===============+
| 1 | 0 | 1 | Problem |
+---+---+---+---------------+
| 1 | 0 | 0 | Privileged(OS)|
+---+---+---+---------------+
| 1 | 1 | 0 | Ultravisor |
+---+---+---+---------------+
| 1 | 1 | 1 | Reserved |
+---+---+---+---------------+

**Normal Mode MSR Settings**

+---+---+---+---------------+
| S | HV| PR|Privilege |
+===+===+===+===============+
| 0 | 0 | 1 | Problem |
+---+---+---+---------------+
| 0 | 0 | 0 | Privileged(OS)|
+---+---+---+---------------+
| 0 | 1 | 0 | Hypervisor |
+---+---+---+---------------+
| 0 | 1 | 1 | Problem (HV) |
+---+---+---+---------------+

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
[ cclaudio: Update the commit message ]
Signed-off-by: Claudio Carvalho <cclaudio@linux.ibm.com>
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
---
arch/powerpc/include/asm/reg.h | 3 +++
1 file changed, 3 insertions(+)

diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index 10caa145f98b..ec3714cf0989 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -38,6 +38,7 @@
#define MSR_TM_LG 32 /* Trans Mem Available */
#define MSR_VEC_LG 25 /* Enable AltiVec */
#define MSR_VSX_LG 23 /* Enable VSX */
+#define MSR_S_LG 22 /* Secure state */
#define MSR_POW_LG 18 /* Enable Power Management */
#define MSR_WE_LG 18 /* Wait State Enable */
#define MSR_TGPR_LG 17 /* TLB Update registers in use */
@@ -71,11 +72,13 @@
#define MSR_SF __MASK(MSR_SF_LG) /* Enable 64 bit mode */
#define MSR_ISF __MASK(MSR_ISF_LG) /* Interrupt 64b mode valid on 630 */
#define MSR_HV __MASK(MSR_HV_LG) /* Hypervisor state */
+#define MSR_S __MASK(MSR_S_LG) /* Secure state */
#else
/* so tests for these bits fail on 32-bit */
#define MSR_SF 0
#define MSR_ISF 0
#define MSR_HV 0
+#define MSR_S 0
#endif

/*
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