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arm64/kvm: Prohibit guest LOR accesses

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We don't currently limit guest accesses to the LOR registers, which we
neither virtualize nor context-switch. As such, guests are provided with
unusable information/controls, and are not isolated from each other (or
the host).

To prevent these issues, we can trap register accesses and present the
illusion LORegions are unssupported by the CPU. To do this, we mask
ID_AA64MMFR1.LO, and set HCR_EL2.TLOR to trap accesses to the following
registers:

* LORC_EL1
* LOREA_EL1
* LORID_EL1
* LORN_EL1
* LORSA_EL1

... when trapped, we inject an UNDEFINED exception to EL1, simulating
their non-existence.

As noted in D7.2.67, when no LORegions are implemented, LoadLOAcquire
and StoreLORelease must behave as LoadAcquire and StoreRelease
respectively. We can ensure this by clearing LORC_EL1.EN when a CPU's
EL2 is first initialized, as the host kernel will not modify this.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Vladimir Murzin <vladimir.murzin@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christoffer Dall <christoffer.dall@linaro.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: kvmarm@lists.cs.columbia.edu
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
This commit is contained in:
Mark Rutland
2018-02-13 13:39:23 +00:00
committed by Christoffer Dall
parent 4a3928c6f8
commit cc33c4e201
4 changed files with 36 additions and 1 deletions
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4
arch/arm64/include/asm/kvm_arm.h
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@@ -25,6 +25,7 @@
/* Hyp Configuration Register (HCR) bits */
#define HCR_TEA (UL(1) << 37)
#define HCR_TERR (UL(1) << 36)
#define HCR_TLOR (UL(1) << 35)
#define HCR_E2H (UL(1) << 34)
#define HCR_ID (UL(1) << 33)
#define HCR_CD (UL(1) << 32)
@@ -64,6 +65,7 @@
/*
* The bits we set in HCR:
* TLOR: Trap LORegion register accesses
* RW: 64bit by default, can be overridden for 32bit VMs
* TAC: Trap ACTLR
* TSC: Trap SMC
@@ -81,7 +83,7 @@
*/
#define HCR_GUEST_FLAGS (HCR_TSC | HCR_TSW | HCR_TWE | HCR_TWI | HCR_VM | \
HCR_TVM | HCR_BSU_IS | HCR_FB | HCR_TAC | \
HCR_AMO | HCR_SWIO | HCR_TIDCP | HCR_RW)
HCR_AMO | HCR_SWIO | HCR_TIDCP | HCR_RW | HCR_TLOR)
#define HCR_VIRT_EXCP_MASK (HCR_VSE | HCR_VI | HCR_VF)
#define HCR_INT_OVERRIDE (HCR_FMO | HCR_IMO)
#define HCR_HOST_VHE_FLAGS (HCR_RW | HCR_TGE | HCR_E2H)