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Commit b0fcd903 authored by Avi Kivity's avatar Avi Kivity
Browse files

KVM: Correctly handle writes crossing a page boundary 



Writes that are contiguous in virtual memory may not be contiguous in
physical memory; so split writes that straddle a page boundary.

Thanks to Aurelien for reporting the bug, patient testing, and a fix
to this very patch.

Signed-off-by: default avatarAurelien Jarno <aurelien@aurel32.net>
Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
parent 0de085bb

drivers/kvm/kvm_main.c

+24 −4
Original line number Diff line number Diff line
@@ -1078,7 +1078,7 @@ static int emulator_write_phys(struct kvm_vcpu *vcpu, gpa_t gpa, 
	return 1;

}



static int emulator_write_emulated(unsigned long addr,

static int emulator_write_emulated_onepage(unsigned long addr,

					   const void *val,

					   unsigned int bytes,

					   struct x86_emulate_ctxt *ctxt)
@@ -1113,6 +1113,26 @@ static int emulator_write_emulated(unsigned long addr, 
	return X86EMUL_CONTINUE;

}



static int emulator_write_emulated(unsigned long addr,

				   const void *val,

				   unsigned int bytes,

				   struct x86_emulate_ctxt *ctxt)

{

	/* Crossing a page boundary? */

	if (((addr + bytes - 1) ^ addr) & PAGE_MASK) {

		int rc, now;



		now = -addr & ~PAGE_MASK;

		rc = emulator_write_emulated_onepage(addr, val, now, ctxt);

		if (rc != X86EMUL_CONTINUE)

			return rc;

		addr += now;

		val += now;

		bytes -= now;

	}

	return emulator_write_emulated_onepage(addr, val, bytes, ctxt);

}



static int emulator_cmpxchg_emulated(unsigned long addr,

				     const void *old,

				     const void *new,