Commit 06add254 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: x86: Shrink the usercopy region of the emulation context 



Shuffle a few operand structs to the end of struct x86_emulate_ctxt and
update the cache creation to whitelist only the region of the emulation
context that is expected to be copied to/from user memory, e.g. the
instruction operands, registers, and fetch/io/mem caches.

Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Reviewed-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 2f728d66

arch/x86/kvm/kvm_emulate.h

+5 −3
Original line number Diff line number Diff line
@@ -334,9 +334,6 @@ struct x86_emulate_ctxt { 
	u8 intercept;

	u8 op_bytes;

	u8 ad_bytes;

	struct operand src;

	struct operand src2;

	struct operand dst;

	union {

		int (*execute)(struct x86_emulate_ctxt *ctxt);

		fastop_t fop;
@@ -364,6 +361,11 @@ struct x86_emulate_ctxt { 
	u8 seg_override;

	u64 d;

	unsigned long _eip;



	/* Here begins the usercopy section. */

	struct operand src;

	struct operand src2;

	struct operand dst;

	struct operand memop;

	/* Fields above regs are cleared together. */

	unsigned long _regs[NR_VCPU_REGS];

arch/x86/kvm/x86.c

+6 −6
Original line number Diff line number Diff line
@@ -235,13 +235,13 @@ static struct kmem_cache *x86_emulator_cache; 


static struct kmem_cache *kvm_alloc_emulator_cache(void)

{

	return kmem_cache_create_usercopy("x86_emulator",

					  sizeof(struct x86_emulate_ctxt),

	unsigned int useroffset = offsetof(struct x86_emulate_ctxt, src);

	unsigned int size = sizeof(struct x86_emulate_ctxt);



	return kmem_cache_create_usercopy("x86_emulator", size,

					  __alignof__(struct x86_emulate_ctxt),

					  SLAB_ACCOUNT,

					  0,

					  sizeof(struct x86_emulate_ctxt),

					  NULL);

					  SLAB_ACCOUNT, useroffset,

					  size - useroffset, NULL);

}



static int emulator_fix_hypercall(struct x86_emulate_ctxt *ctxt);

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