[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH] x86/HVM: correct hvmemul_map_linear_addr() for multi-page case
The function does two translations in one go for a single guest access. Any failure of the first translation step (guest linear -> guest physical), resulting in #PF, ought to take precedence over any failure of the second step (guest physical -> host physical). Bail out of the loop early solely when translation produces HVMTRANS_bad_linear_to_gfn, and record the most relevant of perhaps multiple different errors otherwise. (The choice of ZERO_BLOCK_PTR as sentinel is arbitrary.) Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx> --- a/xen/arch/x86/hvm/emulate.c +++ b/xen/arch/x86/hvm/emulate.c @@ -531,6 +531,20 @@ static int hvmemul_do_mmio_addr(paddr_t return hvmemul_do_io_addr(1, mmio_gpa, reps, size, dir, df, ram_gpa); } +static void *update_map_err(void *err, void *new) +{ + if ( err == ZERO_BLOCK_PTR || err == ERR_PTR(~X86EMUL_OKAY) ) + return new; + + if ( new == ERR_PTR(~X86EMUL_OKAY) ) + return err; + + if ( err == ERR_PTR(~X86EMUL_RETRY) ) + return new; + + return err; +} + /* * Map the frame(s) covering an individual linear access, for writeable * access. May return NULL for MMIO, or ERR_PTR(~X86EMUL_*) for other errors @@ -544,7 +558,7 @@ static void *hvmemul_map_linear_addr( struct hvm_emulate_ctxt *hvmemul_ctxt) { struct vcpu *curr = current; - void *err, *mapping; + void *err = ZERO_BLOCK_PTR, *mapping; unsigned int nr_frames = ((linear + bytes - !!bytes) >> PAGE_SHIFT) - (linear >> PAGE_SHIFT) + 1; unsigned int i; @@ -600,27 +614,28 @@ static void *hvmemul_map_linear_addr( goto out; case HVMTRANS_bad_gfn_to_mfn: - err = NULL; - goto out; + err = update_map_err(err, NULL); + continue; case HVMTRANS_gfn_paged_out: case HVMTRANS_gfn_shared: - err = ERR_PTR(~X86EMUL_RETRY); - goto out; + err = update_map_err(err, ERR_PTR(~X86EMUL_RETRY)); + continue; default: - goto unhandleable; + err = update_map_err(err, ERR_PTR(~X86EMUL_UNHANDLEABLE)); + continue; } *mfn++ = page_to_mfn(page); if ( p2m_is_discard_write(p2mt) ) - { - err = ERR_PTR(~X86EMUL_OKAY); - goto out; - } + err = update_map_err(err, ERR_PTR(~X86EMUL_OKAY)); } + if ( err != ZERO_BLOCK_PTR ) + goto out; + /* Entire access within a single frame? */ if ( nr_frames == 1 ) mapping = map_domain_page(hvmemul_ctxt->mfn[0]); @@ -639,6 +654,7 @@ static void *hvmemul_map_linear_addr( return mapping + (linear & ~PAGE_MASK); unhandleable: + ASSERT(err == ZERO_BLOCK_PTR); err = ERR_PTR(~X86EMUL_UNHANDLEABLE); out: _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
|
Lists.xenproject.org is hosted with RackSpace, monitoring our |