Commit 8034699a authored by Marc Zyngier's avatar Marc Zyngier
Browse files

ARM: KVM: trap VM system registers until MMU and caches are ON 



In order to be able to detect the point where the guest enables
its MMU and caches, trap all the VM related system registers.

Once we see the guest enabling both the MMU and the caches, we
can go back to a saner mode of operation, which is to leave these
registers in complete control of the guest.

Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Reviewed-by: default avatarChristoffer Dall <christoffer.dall@linaro.org>
parent af20814e

arch/arm/include/asm/kvm_arm.h

+2 −1
Original line number Diff line number Diff line
@@ -55,6 +55,7 @@ 
 * The bits we set in HCR:

 * TAC:		Trap ACTLR

 * TSC:		Trap SMC

 * TVM:		Trap VM ops (until MMU and caches are on)

 * TSW:		Trap cache operations by set/way

 * TWI:		Trap WFI

 * TWE:		Trap WFE
@@ -68,7 +69,7 @@ 
 */

#define HCR_GUEST_MASK (HCR_TSC | HCR_TSW | HCR_TWI | HCR_VM | HCR_BSU_IS | \

			HCR_FB | HCR_TAC | HCR_AMO | HCR_IMO | HCR_FMO | \

			HCR_TWE | HCR_SWIO | HCR_TIDCP)

			HCR_TVM | HCR_TWE | HCR_SWIO | HCR_TIDCP)



/* System Control Register (SCTLR) bits */

#define SCTLR_TE	(1 << 30)

arch/arm/kvm/coproc.c

+58 −16
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ 
#include <asm/kvm_host.h>

#include <asm/kvm_emulate.h>

#include <asm/kvm_coproc.h>

#include <asm/kvm_mmu.h>

#include <asm/cacheflush.h>

#include <asm/cputype.h>

#include <trace/events/kvm.h>
@@ -204,6 +205,44 @@ done: 
	return true;

}



/*

 * Generic accessor for VM registers. Only called as long as HCR_TVM

 * is set.

 */

static bool access_vm_reg(struct kvm_vcpu *vcpu,

			  const struct coproc_params *p,

			  const struct coproc_reg *r)

{

	BUG_ON(!p->is_write);



	vcpu->arch.cp15[r->reg] = *vcpu_reg(vcpu, p->Rt1);

	if (p->is_64bit)

		vcpu->arch.cp15[r->reg + 1] = *vcpu_reg(vcpu, p->Rt2);



	return true;

}



/*

 * SCTLR accessor. Only called as long as HCR_TVM is set.  If the

 * guest enables the MMU, we stop trapping the VM sys_regs and leave

 * it in complete control of the caches.

 *

 * Used by the cpu-specific code.

 */

bool access_sctlr(struct kvm_vcpu *vcpu,

		  const struct coproc_params *p,

		  const struct coproc_reg *r)

{

	access_vm_reg(vcpu, p, r);



	if (vcpu_has_cache_enabled(vcpu)) {	/* MMU+Caches enabled? */

		vcpu->arch.hcr &= ~HCR_TVM;

		stage2_flush_vm(vcpu->kvm);

	}



	return true;

}



/*

 * We could trap ID_DFR0 and tell the guest we don't support performance

 * monitoring.  Unfortunately the patch to make the kernel check ID_DFR0 was
@@ -261,33 +300,36 @@ static const struct coproc_reg cp15_regs[] = { 
	{ CRn( 1), CRm( 0), Op1( 0), Op2( 2), is32,

			NULL, reset_val, c1_CPACR, 0x00000000 },



	/* TTBR0/TTBR1: swapped by interrupt.S. */

	{ CRm64( 2), Op1( 0), is64, NULL, reset_unknown64, c2_TTBR0 },

	{ CRm64( 2), Op1( 1), is64, NULL, reset_unknown64, c2_TTBR1 },



	/* TTBCR: swapped by interrupt.S. */

	/* TTBR0/TTBR1/TTBCR: swapped by interrupt.S. */

	{ CRm64( 2), Op1( 0), is64, access_vm_reg, reset_unknown64, c2_TTBR0 },

	{ CRn(2), CRm( 0), Op1( 0), Op2( 0), is32,

			access_vm_reg, reset_unknown, c2_TTBR0 },

	{ CRn(2), CRm( 0), Op1( 0), Op2( 1), is32,

			access_vm_reg, reset_unknown, c2_TTBR1 },

	{ CRn( 2), CRm( 0), Op1( 0), Op2( 2), is32,

			NULL, reset_val, c2_TTBCR, 0x00000000 },

			access_vm_reg, reset_val, c2_TTBCR, 0x00000000 },

	{ CRm64( 2), Op1( 1), is64, access_vm_reg, reset_unknown64, c2_TTBR1 },





	/* DACR: swapped by interrupt.S. */

	{ CRn( 3), CRm( 0), Op1( 0), Op2( 0), is32,

			NULL, reset_unknown, c3_DACR },

			access_vm_reg, reset_unknown, c3_DACR },



	/* DFSR/IFSR/ADFSR/AIFSR: swapped by interrupt.S. */

	{ CRn( 5), CRm( 0), Op1( 0), Op2( 0), is32,

			NULL, reset_unknown, c5_DFSR },

			access_vm_reg, reset_unknown, c5_DFSR },

	{ CRn( 5), CRm( 0), Op1( 0), Op2( 1), is32,

			NULL, reset_unknown, c5_IFSR },

			access_vm_reg, reset_unknown, c5_IFSR },

	{ CRn( 5), CRm( 1), Op1( 0), Op2( 0), is32,

			NULL, reset_unknown, c5_ADFSR },

			access_vm_reg, reset_unknown, c5_ADFSR },

	{ CRn( 5), CRm( 1), Op1( 0), Op2( 1), is32,

			NULL, reset_unknown, c5_AIFSR },

			access_vm_reg, reset_unknown, c5_AIFSR },



	/* DFAR/IFAR: swapped by interrupt.S. */

	{ CRn( 6), CRm( 0), Op1( 0), Op2( 0), is32,

			NULL, reset_unknown, c6_DFAR },

			access_vm_reg, reset_unknown, c6_DFAR },

	{ CRn( 6), CRm( 0), Op1( 0), Op2( 2), is32,

			NULL, reset_unknown, c6_IFAR },

			access_vm_reg, reset_unknown, c6_IFAR },



	/* PAR swapped by interrupt.S */

	{ CRm64( 7), Op1( 0), is64, NULL, reset_unknown64, c7_PAR },
@@ -324,9 +366,9 @@ static const struct coproc_reg cp15_regs[] = { 


	/* PRRR/NMRR (aka MAIR0/MAIR1): swapped by interrupt.S. */

	{ CRn(10), CRm( 2), Op1( 0), Op2( 0), is32,

			NULL, reset_unknown, c10_PRRR},

			access_vm_reg, reset_unknown, c10_PRRR},

	{ CRn(10), CRm( 2), Op1( 0), Op2( 1), is32,

			NULL, reset_unknown, c10_NMRR},

			access_vm_reg, reset_unknown, c10_NMRR},



	/* AMAIR0/AMAIR1: swapped by interrupt.S. */

	{ CRn(10), CRm( 3), Op1( 0), Op2( 0), is32,
@@ -340,7 +382,7 @@ static const struct coproc_reg cp15_regs[] = { 


	/* CONTEXTIDR/TPIDRURW/TPIDRURO/TPIDRPRW: swapped by interrupt.S. */

	{ CRn(13), CRm( 0), Op1( 0), Op2( 1), is32,

			NULL, reset_val, c13_CID, 0x00000000 },

			access_vm_reg, reset_val, c13_CID, 0x00000000 },

	{ CRn(13), CRm( 0), Op1( 0), Op2( 2), is32,

			NULL, reset_unknown, c13_TID_URW },

	{ CRn(13), CRm( 0), Op1( 0), Op2( 3), is32,

arch/arm/kvm/coproc.h

+4 −0
Original line number Diff line number Diff line
@@ -153,4 +153,8 @@ static inline int cmp_reg(const struct coproc_reg *i1, 
#define is64		.is_64 = true

#define is32		.is_64 = false



bool access_sctlr(struct kvm_vcpu *vcpu,

		  const struct coproc_params *p,

		  const struct coproc_reg *r);



#endif /* __ARM_KVM_COPROC_LOCAL_H__ */

arch/arm/kvm/coproc_a15.c

+1 −1
Original line number Diff line number Diff line
@@ -34,7 +34,7 @@ 
static const struct coproc_reg a15_regs[] = {

	/* SCTLR: swapped by interrupt.S. */

	{ CRn( 1), CRm( 0), Op1( 0), Op2( 0), is32,

			NULL, reset_val, c1_SCTLR, 0x00C50078 },

			access_sctlr, reset_val, c1_SCTLR, 0x00C50078 },

};



static struct kvm_coproc_target_table a15_target_table = {

arch/arm/kvm/coproc_a7.c

+1 −1
Original line number Diff line number Diff line
@@ -37,7 +37,7 @@ 
static const struct coproc_reg a7_regs[] = {

	/* SCTLR: swapped by interrupt.S. */

	{ CRn( 1), CRm( 0), Op1( 0), Op2( 0), is32,

			NULL, reset_val, c1_SCTLR, 0x00C50878 },

			access_sctlr, reset_val, c1_SCTLR, 0x00C50878 },

};



static struct kvm_coproc_target_table a7_target_table = {

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