From: Volodymyr Babchuk Date: Thu, 23 May 2024 08:17:30 +0000 (+0200) Subject: arm/vpci: honor access size when returning an error X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=7db7bd0f319fe7f19a6904e75c53adf891fa2dac;p=people%2Froyger%2Fxen.git arm/vpci: honor access size when returning an error Guest can try to read config space using different access sizes: 8, 16, 32, 64 bits. We need to take this into account when we are returning an error back to MMIO handler, otherwise it is possible to provide more data than requested: i.e. guest issues LDRB instruction to read one byte, but we are writing 0xFFFFFFFFFFFFFFFF in the target register. Signed-off-by: Volodymyr Babchuk Signed-off-by: Stewart Hildebrand Acked-by: Julien Grall --- diff --git a/xen/arch/arm/vpci.c b/xen/arch/arm/vpci.c index 3bc4bb5508..b63a356bb4 100644 --- a/xen/arch/arm/vpci.c +++ b/xen/arch/arm/vpci.c @@ -29,6 +29,8 @@ static int vpci_mmio_read(struct vcpu *v, mmio_info_t *info, { struct pci_host_bridge *bridge = p; pci_sbdf_t sbdf = vpci_sbdf_from_gpa(bridge, info->gpa); + const unsigned int access_size = (1U << info->dabt.size) * 8; + const register_t invalid = GENMASK_ULL(access_size - 1, 0); /* data is needed to prevent a pointer cast on 32bit */ unsigned long data; @@ -39,7 +41,7 @@ static int vpci_mmio_read(struct vcpu *v, mmio_info_t *info, return 1; } - *r = ~0ul; + *r = invalid; return 0; }