From 4609fc8eb04e6af531d86923c9d057f32a96b7d8 Mon Sep 17 00:00:00 2001 From: Andrew Cooper Date: Thu, 28 May 2020 14:03:22 +0100 Subject: [PATCH] x86/hvm: Improve error information in handle_pio() MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit domain_crash() should always have a message which is emitted even in release builds, so something more useful than this is presented to the user. (XEN) domain_crash called from io.c:171 (XEN) domain_crash called from io.c:171 (XEN) domain_crash called from io.c:171 ... To avoid possibly printing stack rubble, initialise data to ~0 right away. Furthermore, the maximum access size is 4, so drop data from long to int. Signed-off-by: Andrew Cooper Reviewed-by: Roger Pau Monné Acked-by: Jan Beulich --- xen/arch/x86/hvm/io.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/xen/arch/x86/hvm/io.c b/xen/arch/x86/hvm/io.c index a5b0a23f06..724ab44a76 100644 --- a/xen/arch/x86/hvm/io.c +++ b/xen/arch/x86/hvm/io.c @@ -132,13 +132,15 @@ bool handle_pio(uint16_t port, unsigned int size, int dir) { struct vcpu *curr = current; struct hvm_vcpu_io *vio = &curr->arch.hvm.hvm_io; - unsigned long data; + unsigned int data; int rc; ASSERT((size - 1) < 4 && size != 3); if ( dir == IOREQ_WRITE ) data = guest_cpu_user_regs()->eax; + else + data = ~0; /* Avoid any risk of stack rubble. */ rc = hvmemul_do_pio_buffer(port, size, dir, &data); @@ -151,7 +153,7 @@ bool handle_pio(uint16_t port, unsigned int size, int dir) if ( dir == IOREQ_READ ) { if ( size == 4 ) /* Needs zero extension. */ - guest_cpu_user_regs()->rax = (uint32_t)data; + guest_cpu_user_regs()->rax = data; else memcpy(&guest_cpu_user_regs()->rax, &data, size); } @@ -167,7 +169,9 @@ bool handle_pio(uint16_t port, unsigned int size, int dir) break; default: - gdprintk(XENLOG_ERR, "Weird HVM ioemulation status %d.\n", rc); + gprintk(XENLOG_ERR, "Unexpected PIO status %d, port %#x %s 0x%0*x\n", + rc, port, dir == IOREQ_WRITE ? "write" : "read", + size * 2, data & ((1u << (size * 8)) - 1)); domain_crash(curr->domain); return false; } -- 2.39.5